892 terms

DP Biology Vocabulary

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Cell theory
theory that states that all organisms are composed of cells, and that all cells come from pre-existing cells.
Centi-
metric prefix 1/100th or 1 _ 10-2.
Coarse focus dial
used to initially focus a light microscope on a specimen.
Differentiation
the alteration of a cell's morphology and physiology through changes in gene expression.
Emergent property
a property of a system that emerges from the interaction of the elements of the system.
Gene expression
the synthesis of a functional gene product, often protein, but also rRNA, tRNA, or snRNA.
Growth
an increase in physical size.
Homeostasis
the process in which an organism regulates activities within cells and their bodies to keep conditions stable.
Magnification
ratio of image size to actual size.
Metabolism
the sum of all of the chemical reactions that occur within an organism or within a cell.
Micro-
metric prefix 1 _ 10-6.
Milli-
metric prefix 1 _ 10-3.
Nano-
metric prefix 1 _ 10-9.
Objective lens
the part of the microscope that gathers light from the specimen and focuses it to produce a real image.
Paramecium
genus of single-celled ciliated organisms.
Reductionism
an approach to science that holds that a complex system can be best understood as the sum of its parts, and that variables can be studied in isolation.
Response
in behavioural science, the behaviour that is the consequence of a stimulus.
Scale bar
a means of visually indicating the magnification of an image.
Stargardt's disease
a degenerative eye disease that has been the target of stem cell research.
Stem cell
a relatively undifferentiated cell that can give rise to other types of cells and retains the ability to divide.
Surface area to volume ratio
a variable that decreases as cells grow, so that it sets a limit to the size of cells.
System
a level of organization that emerges due to the interaction of elements.
Tissue
a group of cells with a common function and structure.
70S
the size of prokaryotic ribosomes.
80S
the size of eukaryotic ribosomes.
Archaea
a domain of prokaryotes.
Bacteria
a domain of prokaryotes.
Binary fission
method of prokaryotic cell division.
Cell wall
non-living carbohydrate-based extracellular material.
Compartmentalization
seen in eukaryotes; consequence of organelles being membrane-bound.
Endoplasmic reticulum (ER)
site of synthesis of proteins destined for export or for secretion.
Eukaryote
organisms with membrane-bound nuclei.
Exocrine glands
glands that secrete their products into ducts.
Extracellular matrix
a network of material that is secreted by cells that serves to support, strengthen, and organize cells.
Flagellum
a relatively long extension of the cell used in locomotion.
Golgi body
a eukaryotic organelle that modifies proteins after translation.
Histone
a protein associated with DNA that plays a role in gene expression and the packing of DNA.
Lysosome
a cellular organelle involved in cellular digestion.
Naked DNA
DNA not associated with histones or histone-like proteins.
Nucleoid
a region of the prokaryotic cell where DNA is located.
Nucleus
membrane-bound organelle found in eukaryotes that contains DNA; it is the site of replication and transcription.
Organelle
a sub-cellular structure or membrane-bound compartment with a distinct structure and function.
Palisade mesophyll
photosynthetic tissue below the epidermis in a leaf.
Pilli
extensions of the prokaryotic cell surface membrane used for reproduction.
Plasmid
extra-chromosomal DNA in a prokaryote.
Prokaryote
category of a cell without a membrane-bound nucleus: archaea and bacteria.
rER
rough ER - ER with ribosomes attached.
Resolution
the ability to see adjacent objects or structures as distinct from each other.
Ribosome
organelle involved in protein synthesis.
Scanning electron microscope
an electron microscope that generates a three-dimensional image.
sER
endoplasmic reticulum that synthesizes new membrane and does not have ribosomes attached.
Svedberg unit
unit of molecule size based on the position that material settles out in a centrifuge tube after spinning. Larger particles tend to settle out faster and so have higher Svedberg values.
Transmission electron microscope
an electron microscope that produces two-dimensional images.
Ultrastructure
the detailed structure of a biological entity.
Amphipathic
molecule that has hydrophobic and hydrophilic regions.
Cholesterol
a lipid that prevents the membrane from becoming too and also prevents it from crystalizing.
Davson-Danielli model
model of the cell membrane in which the phospholipid bilayer is between two layers of protein.
Electron carriers
proteins arranged in chains on the membrane to allow the transfer of electrons from one carrier to another.
Fluid mosaic model
a model conceived by S.J. Singer and Garth Nicolson in 1972 to describe the observed structural features of biological membranes.
Fluidity
refers to the viscosity of a lipid bilayer of the membrane that allows it to change shape.
Glycoproteins
proteins that contain oligosaccharide chains.
Hormone-binding sites
proteins on the outside of the membrane that allow specific hormones to bind.
Hydrophilic
molecules that are attracted to water.
Hydrophobic
molecules that are not attracted to water but are attracted to each other.
Integral proteins
proteins embedded in the phospholipid bilayer.
Peripheral proteins
proteins on the surface of the plasma membrane.
Permeability
the rate of passive diffusion of molecules through the membrane, which depends on the electric charge, size, and polarity of the molecule.
Phospholipid bilayer
two layers of phospholipids arranged so that their hydrophobic tails are projecting inwards while their polar head groups are on the outside surfaces.
Phospholipids
a lipid consisting of a glycerol bound to two fatty acids and a phosphate group.
Singer-Nicholson model
current model of membrane structure that incorporates a fluid mosaic structure in a discontinuous lipid bilayer.
Transport pumps
proteins in the plasma membrane that release energy and use it to move substances across the membrane.
Active transport
movement of substances across membranes using energy in the form of ATP.
ATP (adenosine triphosphate)
The energy molecule.
Concentration gradient
a gradient resulting from an unequal distribution of ions across the cell membrane.
Diffusion
passive movement of particles from a region of higher concentration to a region of lower concentration.
Endocytosis
the process in which the cell takes in materials from the outside by infolding of the membrane to form a vesicle.
Exocytosis
the process in which the cell releases materials to the outside by discharging them as membrane-bounded vesicles that pass through the cell membrane.
Facilitated diffusion
diffusion through a membrane that requires proteins.
Hypertonic
a more concentrated solution relative to another fluid.
Hypotonic
a less concentrated solution relative to another fluid.
Osmoregulation
control of the water balance of a living organism.
Osmosis
passive movement of water molecules from a region of lower solute concentration to a region of higher solute concentration.
Secretion
when material is released from a cell.
Semi-permeable membrane
membrane that allows some substances to diffuse through but not others. Transport pumps proteins in the plasma membrane that use ATP to move substances across the membrane. Vesicles a bubble-like membranous structure that stores and transports cellular products.
Endosymbiotic theory
a theory that some eukaryotic organelles, such as mitochondria and chloroplasts, originated as free-living prokaryotes that invaded primitive eukaryotic cells.
Genetic code
a nearly universal sequence of nucleotides in DNA that determines the specific amino acid sequence in the synthesis of proteins.
Louis Pasteur
French scientist that proved, among other things, that the emergent growth of bacteria in nutrient broths is due to biogenesis, not spontaneous generation.
Spontaneous generation
old theory that believed in the formation of living organisms from non-living matter.
Sterilization
technique used for the elimination of microbiological organisms to achieve a sterile microbial environment.
Anaphase
the stage of mitosis and meiosis in which the chromosomes move to opposite ends of the nuclear spindle.
Binary fission
a type of asexual reproduction common among prokaryotes where one cell divides giving rise to two cells, each having the potential to grow to the size of the original cell.
Cancer
general term for more than 100 diseases that are characterized by uncontrolled, abnormal growth of cells.
Cell plate
a membrane that forms midway between dividing plant cells during cytokinesis and later becomes the cell wall.
Centrioles
a self-replicating cylindrical organelle that is involved in the process of nuclear division.
Centromere
the region joining the two sister chromatids where it becomes attached to the spindle fibres.
Chromosomes
linear strand of DNA bonded to proteins in the nucleus of eukaryotic cells that carries the genetic information.
Cyclins
a family of closely related proteins that regulate the cell cycle in eukaryotic cells.
Cytokinesis
the division of the cytoplasm and the plasma membrane, following the division of the nucleus, resulting in two cells in mitosis.
Equatorial plate
the figure formed by the chromosomes in the centre of the spindle during mitosis.
Metaphase
stage in mitosis in which chromosomes become arranged at the equatorial plate.
Metastasis
characteristic of malignant tumours of transferring the disease from one organ to another not directly connected with it.
Microtubule fibres
hollow protein tubes seen during the mitosis of animal cells.
Mitosis
the process where a single cell divides into two identical cells, each containing the same number of chromosomes and genetic content as that of the original cell.
Mitotic index
the ratio between the number of cells in mitosis to the total number of cells.
Mutagens
chemical agents that increase the rate of genetic mutation.
Oncogenes
a gene that causes normal cells to change into cancerous tumour cells.
Prophase
first stage of mitosis during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears.
Sister chromatids
two identical strands of DNA joined by a common centromere.
Spindle fibres
network of filaments that collectively form a mitotic spindle in mitosis. They are involved in moving the chromosomes during nuclear division.
Supercoiling
twisting in the opposite direction to the turns of the double helix during the first stage of mitosis.
Telophase
the final stage of mitosis in which the separated chromosomes reach the opposite poles of the dividing cell and the nuclei of the daughter cells form around them.
Tumours
abnormal proliferation of cells, either benign or malignant.
Amino acid
building block of proteins that consists of a basic amino group (NH2), an acidic carboxylic group (COOH), a hydrogen atom (-H), and an organic side group (-R) attached to the carbon atom.
Anabolism
the synthesis of complex molecules from simpler molecules, including the formation of macromolecules from monomers by condensation reactions.
Carbohydrates
organic compounds with the general formula (CH2O)n, including sugars, starches, and celluloses, that are an important source of food and energy for animals.
Catabolism
the breakdown of complex molecules into simpler molecules, including the hydrolysis of macromolecules into monomers.
Covalent bonds
a chemical bond formed by the sharing of one or more electrons, especially pairs of electrons, between atoms.
Disaccharide
sugar (carbohydrate) composed of two monosaccharides joined by condensation.
Glucose
a simple monosaccharide sugar (C6H12O6) that serves as the main source of energy and as an important metabolic substrate for most living organisms.
Lipids
organic compounds, including the fats, oils, waxes, sterols, and triglycerides, that are insoluble in water, but soluble in non-polar organic solvents.
Metabolism
the process involving biochemical reactions of life.
Monosaccharide
the simplest form of carbohydrate (examples include fructose, glucose, and ribose) that constitutes the building blocks of more complex forms of sugar.
Nucleic acids
linear chains (DNA or RNA) of monomeric nucleotides, whereby each monomeric unit is composed of phosphoric acid, sugar, and nitrogenous base.
Peptide bonds
a covalent bond that joins amino acids, at the carboxyl group of one amino acid to the amino group of the other amino acid, with the release of a molecule of water.
Phospholipids
a lipid consisting of a glycerol bound to two fatty acids and a phosphate group.
Polypeptides
a polymer of amino acids joined together by peptide bonds.
Protein
organic molecule composed of polymers of amino acids joined together by peptide bonds and taking a particular three-dimensional shape.
Ribose
a monosaccharide (chemical formula C5H10O5) found in RNA and other metabolically important compounds.
Saturated fat
a fatty acid with all potential hydrogen binding sites filled.
Saturated fatty acid
a form of fatty acid that lacks unsaturated linkages between carbon atoms.
Steroids
lipid-based hormones that are related to the four-ring structure of cholesterol.
Triglycerides
an energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid.
Urea
a molecule created from ammonia and carbon dioxide as the final nitrogenous excretion product of many organisms.
Adhesion
the force by which individual molecules cling to surrounding material and surfaces.
Boiling point
the temperature at which the vapour pressure of a given liquid reaches atmospheric pressure and thus starts to boil (100°C for water).
Cohesion
the force by which individual molecules stick together.
Freezing point
the temperature at which a liquid solidifies (0°C for water).
Specific heat capacity
the amount of energy required to raise the temperature of water by one degree Celsius (water has to absorb 4.184 joules of heat for the temperature of one gram of water to increase by 1°C).
Hydrogen bond
a weak bond caused by electrostatic attraction between a positively-charged part of one molecule and a negatively-charged part of another.
Hydrophilic
molecules capable of interacting with water through hydrogen bonding (having an affinity for water).
Hydrophobic
molecules that lack an affinity for water (water insoluble).
Methane
a light, colourless gas (CH4).
Polarity
property of having distinct and opposite charges (poles).
Solubility
the property of a substance of being soluble (dissolved).
Solvent
a liquid in which substances (or solutes) are dissolved to form a solution.
Surface tension (of water)
the intermolecular hydrogen bonds between molecules of water at the surface.
Transparency
property that allows light to penetrate molecules of water.
Amylopectin
a soluble polysaccharide and highly-branched polymer of glucose found in plants as one of the two components of starch (the other being amylose).
Amylose
a polysaccharide found in plants as one of the two components of starch (making up approximately 20-30% of the structure).
Body mass index (BMI)
a measure for human body shape based on an individual's mass and height (kg/m2).
Cellulose
a polysaccharide with the formula (C6H10O5)n, consisting of a linear chain of between several hundred to over ten thousand _-linked D-glucose units.
Condensation
formation of larger molecules involving the removal of water from smaller component molecules.
Disaccharide
a sugar (carbohydrate) composed of two monosaccharides joined by condensation.
Fatty acids
any of the group of a long chain of hydrocarbon derived from the breakdown of fats having a single carboxylic group and aliphatic tail.
Glycerol
a metabolic intermediate and structural component of the major classes of biological lipids, triglycerides, and phospholipids.
Glycogen
a branched polymer of glucose that is mainly produced in liver and muscle cells, and functions as secondary long-term energy storage in animal cells.
Isomers
chemical compounds of the same chemical formula but different structure (cis or trans).
Lactose
a disaccharide sugar that is commonly found in milk and consists of galactose and glucose.
Lipids
organic compounds, including the fats, oils, waxes, sterols, and triglycerides, that are insoluble in water,but soluble in non-polar organic solvents.
Maltose
a disaccharide formed when two glucose monomers join together.
Monomers
consist of a single component.
Monosaccharide
the simplest form of carbohydrate (for example fructose, glucose, and ribose) that constitutes the building blocks of a more complex form of sugars.
Monounsaturated
an unsaturated molecule that contains only one double or triple bond in the carbon chain.
Polymer
a compound made up of several repeating units (monomers).
Polysaccharide
a complex carbohydrate composed of a chain of monosaccharides joined together by glycosidic bonds.
Polyunsaturated
a type of molecule that contains more than one double or triple bond in the carbon chain.
Saturated fatty acids
a form of fatty acid that lacks unsaturated linkages between carbon atoms.
Starch
a polysaccharide carbohydrate (C6H10O5)n found in plants that consists of a large number of glucose monosaccharides.
Sucrose
a disaccharide composed of the monosaccharides glucose and fructose.
Triglycerides
an energy-rich compound made up of a single molecule of glycerol and three molecules of fatty acid.
Unsaturated fatty acid
a form of fatty acid that contains more than one double bond between carbon atoms.
Albumin
the main protein of human plasma. Its main function is to regulate the osmotic pressure of blood.
Amino acids
building block of proteins consisting of the basic amino group (NH2), the acidic carboxylic group (COOH), a hydrogen atom (-H), and an organic side group (R) attached to the carbon atom.
Amino group
NH2
Carboxylic group
COOH
Collagen
a glycoprotein that forms strong fibres, found in connective tissue and bone (the most abundant protein in the animal kingdom).
Condensation
formation of larger molecules from smaller component molecules involving the removal of water.
Denaturation
a structural change in a protein that results in a permanent loss of biological properties.
Dipeptide
two amino acids linked together.
Gene
a heritable section of DNA that controls a specific trait.
Immunoglobulins
group of large glycoproteins that function as antibodies in the immune response by binding with specific antigens.
Insulin
a hormone that lowers blood glucose levels by synthesizing glycogen.
Peptide bond
a covalent bond that joins amino acids, at the carboxyl group of one amino acid to the amino group of the other amino acid, with the release of a molecule of water.
Polypeptides
a polymer of amino acids joined together by peptide bonds.
Protein
organic molecule composed of polymers of amino acids joined together by peptide bonds and taking a particular three-dimensional shape.
Proteome
the complete set of proteins that can be expressed by the genetic material of an organism.
Rhodopsin
a visual pigment consisting of retinal and opsin.
Ribosome
cell organelle functioning as the site of protein synthesis.
Rubisco (ribulose carboxylase)
is the enzyme that catalyses the first step of photosynthesis (probably the most abundant protein on Earth).
Active site
the specific portion of an enzyme that attaches to the substrate.
Catalase
an enzyme found in the blood, and in most living cells, that catalyses the decomposition of hydrogen peroxide into water and oxygen.
Denaturation
a structural change in a protein that alters its three-dimensional shape and causes the loss of its biological properties.
Enzyme activity
a measure of the ability of an enzyme to catalyse a specific reaction.
Enzymes
a class of proteins that catalyses chemical reactions.
Hydrolysis
decomposition of a chemical compound by reaction with water.
Lactase
the enzyme responsible for catalysing the split of lactose into galactose and glucose.
Lactose
a disaccharide (C12H22O11) found in milk that may be hydrolysed to yield glucose and galactose.
Metabolism
all of an organism's chemical processes.
Substrate
the substance on which an enzyme works.
Adenine
an organic base found in DNA and RNA in which it pairs with thymine (or uracil).
Complementary base pairs
the standard arrangement of bases in nucleotides in relation to their opposite pairing, such as cytosine paired with guanine and adenine with thymine (or uracil in RNA).
Cytosine
an organic base found in DNA and RNA in which it pairs with guanine.
DNA polymerase
an enzyme that catalyses the elongation of new DNA during replication.
DNA
a nucleic acid consisting of two long chains of nucleotides twisted into a double helix that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA.
Guanine
an organic base found in DNA and RNA in which it pairs with cytosine.
Hydrogen bond
a chemical bond in which a hydrogen atom of one molecule is attracted to an electronegative atom of another molecule.
Nucleic acids
biological molecules, such as DNA or RNA, composed of nucleotides that control cellular functions and heredity.
Nucleotides
the building blocks of nucleic acids consisting of a five-carbon sugar, a nitrogenous base, and a phosphate group.
Polymer
a large molecule consisting of many identical or similar monomers linked together.
RNA
a nucleic acid consisting of a long single-stranded chain of nucleotides involved in protein synthesis.
RNA polymerase
an enzyme that links together the growing chain of RNA during transcription.
Thymine
an organic base found in DNA, but not in RNA, that pairs with adenine.
Uracil
a nitrogen-containing base found in RNA, but not in DNA, that pairs with adenine.
Amino acid
building block of proteins consisting of a basic amino group (NH2), an acidic carboxylic group (COOH), a hydrogen atom (-H), and an organic side group (R) attached to the carbon atom.
Anticodon
three consecutive bases on tRNA that are complementary to a codon on mRNA.
Codon
each sequence of three bases standing for one of the 20 possible amino acids.
Complementary base pairing
is the standard arrangement of bases in nucleotides in relation to their opposite pairing, such as cytosine paired with guanine and adenine with thymine (or uracil in RNA).
Degenerate code
there are more codons (64) than there are amino acids to be coded, so most amino acids are coded by more than one code.
DNA polymerase
an enzyme that catalyses the elongation of new DNA during replication.
Genetic code
the order of bases in DNA that determines the sequence of amino acids in proteins.
Helicase
an enzyme involved in DNA replication, responsible for unwinding the double helix.
Hydrogen bonds
a chemical bond in which a hydrogen atom of one molecule is attracted to an electronegative atom of another molecule.
Insulin
a hormone that lowers blood glucose levels by synthesizing glycogen.
Messenger RNA (mRNA)
a type of RNA that attaches to ribosomes and specifies the sequence of amino acids in a protein.
Nucleotides
the building blocks of nucleic acids consisting of a five-carbon sugar, a nitrogenous base, and a phosphate group.
Polymerase chain reaction (PCR)
a technique for amplifying DNA in vitro.
Polypeptides
a polymer of amino acids joined together by peptide bonds.
Polysomes
several ribosomes that are attached to the same mRNA at one time.
Replication of DNA
making a copy of a DNA molecule.
Ribosomes
cell organelle that functions as the site of protein synthesis.
RNA polymerase
an enzyme that links together the growing chain of RNA during transcription.
Semi-conservative replication
in the process of DNA synthesis each original strands of the molecule acts as a template on which a new complementary strand is created.
Taq DNA polymerase
a heat resistant enzyme found in the bacillus Thermus aquaticus, which lives in hot springs, that can endure the high temperatures of the polymerase chain reaction.
Transcription
when the DNA sequence of bases is converted into mRNA.
Translation
when the sequence of bases on mRNA is decoded into an amino acid sequence (proteins).
Transfer RNA (tRNA)
an RNA molecule that brings specific amino acids that match the codons in the mRNA.
Aerobic cell respiration
respiration requiring oxygen, involving the oxidation of glucose to carbon dioxide and water.
Anaerobic cell respiration
respiration in the absence of oxygen, involving the formation of lactic acid or ethanol.
Adenosine triphosphate (ATP)
a nucleotide that releases energy when its phosphate bonds are hydrolysed.
Carbon dioxide (CO2)
molecule resulting from oxidation of organic carbon compounds, and formed in the tissues and eliminated by the lungs.
Cell respiration
the controlled release of energy from organic compounds to produce ATP.
Ethanol
alcohol formed by microbial fermentation of carbohydrates.
Fermentation
anaerobic breakdown of glucose with the end-products of ethanol and carbon dioxide or lactic acid.
Glucose
monosaccharide that is an end product of carbohydrate metabolism, and is the chief source of energy for living organisms.
Metabolic pathways
a series of enzymatic reactions that converts one biological material to another.
Respirometer
apparatus for the measurement of respiratory gaseous exchange.
Yeasts
a unicellular fungus that lives in liquid or moist habitats.
Absorption spectrum
range of wavelengths of light that a pigment is able to absorb.
Action spectrum
range of wavelengths of light within which photosynthesis takes place.
Chlorophyll
main photosynthetic pigment of green plants.
Chloroplast
cell organelle that is the site of photosynthesis.
Chromatography
a method of separating and identifying the components of a complex mixture by differential movement through a two-phase system.
Limiting factors
an environmental factor, such as carbon dioxide or light intensity, that controls the process of photosynthesis.
Nanometre
one billionth (10-9) of a metre.
Photolysis of water
chemical decomposition of water induced by light.
Photosynthesis
the production of carbon compounds in cells using light energy.
Rate of photosynthesis
the rate of conversion of carbon dioxide and water to photosynthetic products.
Wavelength
the distance between peaks of a wave of light, which determines its colour.
Allele
one of the possible alternatives of a gene, occupying a specific position on a chromosome, that controls the same trait.
Base sequence
the order of nucleotide bases in a DNA molecule.
Chromosome
a structure within the cell that bears the genetic material as a thread-like linear strand of DNA with the genes in a linear order (the human species has 23 pairs).
Deletion
a type of chromosomal aberration in which a segment of the chromosome is removed or lost.
Frame shift
a genetic mutation, caused by a deletion or insertion in a DNA sequence, that shifts the way the sequence is read.
Genbank database
an open access, annotated collection of all publicly available nucleotide sequences and their protein translations.
Gene mapping
the process of determining the locus for a particular biological trait.
Gene
a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.
Genome
the total genetic material of an organism.
Glutamic acid
a non-essential amino acid, occurring in proteins, that is replaced by valine in cases of sickle cell anaemia.
Haemoglobin
the oxygen-carrying pigment of red blood cells that gives them their red colour and serves to convey oxygen to the tissues.
Human Genome Project
an international scientific research project to determine the sequence of chemical base pairs that make up human DNA, and to identify and map all of the genes of the human genome.
Insertion
the addition by mutation of one or more nucleotides to a chromosome.
Locus
the position of a gene on the chromosome (loci plural).
Mutation
a change of the DNA sequence within a gene or chromosome of an organism that results in the creation of a new character or trait not found in the parental type.
Plasmid
the DNA of a prokaryote in the circular chromosome.
Point mutation
the exchange of a single nucleotide for another in the DNA sequence of a gene.
Polypeptide
a peptide, such as a small protein, containing many molecules of amino acids, typically between 10 and 100.
Sickle cell anaemia
an autosomal recessive anaemia due to substitution of a single amino acid (valine for glutamic acid) characterized by red blood cell becoming sickle-shaped and non-functional.
Transcription
the process of copying of DNA into messenger RNA in gene expression.
Valine
an essential amino acid occurring in proteins that replaces glutamic acid in cases of sickle cell anaemia.
Allele
one of the possible alternatives of a gene, occupying a specific position on a chromosome, that controls the same trait.
Autoradiography
technique that relies on the emission of radioactive particles from within the subject to produce an image.
Autosomes
chromosomes that do not determine sex.
Centromere
region of the chromosome that becomes attached to the spindle fibres during cell division.
Chromosome
a structure within the cell that bears the genetic material as a thread-like linear strand of DNA that carry the genes in a linear order (the human species has 23 pairs).
Diploid cells
have nuclei containing two sets of chromosomes (2n), one set from each parent.
Down syndrome
a human genetic disease resulting from having an extra chromosome 21 (characterized by having a delay in mental development).
Gene
a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.
Genome
the total genetic material of an organism.
Haploid cells
have one chromosome of each pair (have one full set of the chromosomes that are found in its species).
Histones
globular proteins associated to chromosomes in eukaryotic cells.
Homologous chromosomes
chromosome pairs with genes for the same characteristics at corresponding loci.
Karyogram
shows the chromosomes of an organism in homologous pairs of decreasing length.
Karyotype
a method of organizing the chromosomes of a cell in relation to number, size, and type.
Locus
the position of the gene on the chromosome (loci plural).
Naked DNA
the DNA in prokaryotic cells that is not associated with proteins.
Plasmid
the DNA of prokaryote in the circular chromosome.
Sequencing of DNA
to determine the order of nucleotide bases in a DNA molecule.
Sex chromosomes
the pair of chromosomes responsible for determining the sex of an individual.
Sister chromatids
replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis.
Staining
treating (specimens for the microscope) with a reagent or dye that makes certain structures visible without affecting others.
Allele
one of the possible alternative of a gene, occupying a specific position on a chromosome, that controls the same trait.
Amniocentesis
a procedure used to diagnose genetic defects in the early stages of pregnancy; it involves collecting amniotic fluid using a needle and syringe.
Chorionic villus sampling
technique for diagnosing genetic defects while a foetus is in the uterus. A small sample of the placenta is removed and analysed.
Crossing over
exchange of genetic material between non-sister chromatids during meiosis I.
Diploid
a cell containing two sets of chromosomes (2n), one from each parent.
Down syndrome
a human genetic disease resulting from having an extra chromosome 21 (characterized by having a delay in mental development).
Gametes
one of two haploid reproductive cells, egg or sperm, whose union is necessary in sexual reproduction to produce a diploid zygote.
Germ-line cells
the cellular lineage of a sexually reproducing organism from which eggs and sperm are derived.
Haploid cells
have one chromosome of each pair (have one full set of the chromosomes that are found in its species).
Homologous chromosomes
chromosome pairs with genes for the same characteristics at corresponding loci.
Karyotype
a method of organizing the chromosomes of a cell in relation to number, size, and type.
Meiosis
the process of cell division in sexually reproducing organisms that reduces the number of chromosomes in reproductive cells from diploid to haploid.
Non-disjunction
an error during mitosis or meiosis in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart.
Random orientation
the orientation of homologous chromosomes in the spindle axis during metaphase I is random and either maternal or paternal homologue may orient towards a given pole.
Sister chromatids
replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis.
Allele
one of the possible alternatives of a gene, occupying a specific position on a chromosome, that controls the same trait.
Allele mask
when one allele covers the phenotypic expression of another allele at the same gene locus.
Autosomal genes
chromosomes that do not determine sex.
Co-dominant alleles
two alleles at a particular locus that have different effects and are distinguishable in a heterozygous individual (e.g. AB blood groups).
Colour blindness
an abnormal condition caused by an X-linked recessive allele and characterized by the inability to clearly distinguish different colours of the visible light spectrum.
Cystic fibrosis
a mutation in a gene that changes a protein that regulates the movement of salt in and out of cells; characterized by the production of thick and sticky mucus.
Dominant alleles
the allele that is fully expressed in the phenotype of a heterozygote.
Gametes
one of two haploid reproductive cells, egg or sperm, whose union is necessary in sexual reproduction to produce a diploid zygote.
Gene
a hereditary unit consisting of a sequence of DNA that occupies a specific location on a chromosome and determines a particular characteristic in an organism.
Genotype
the genetic constitution of an organism.
Haploid cells
have one chromosome of each pair (have one full set of the chromosomes that are found in its species).
Haemophilia
a sex-linked inheritable disease characterized by loss or impairment of the normal clotting ability of blood, so that a minor wound may result in fatal bleeding.
Huntington's disease
caused by a genetic defect on chromosome 4; the defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to.
Mutagen
a chemical or physical agent that interacts with DNA and causes a mutation.
Phenotype
the physical and physiological traits of an organism.
Punnett grid (or Punnett square)
a tool that helps to show all possible allelic combinations of gametes in a cross of parents with known genotypes in order to predict the probability of their offspring possessing certain sets of alleles.
Recessive allele
an allele that has an effect on the phenotype only when present in the homozygous state.
Sex-linked inheritance
traits controlled by genes located on one sex chromosome but not the other.
Zygotes
the diploid product of the fusion of haploid gametes (a fertilized egg).
Clones
a group of genetically identical cells or individuals.
DNA ligase
a linking enzyme essential for DNA replication.
DNA profiling (DNA fingerprinting)
the analysis of a small amount of genetic material, which is as unique per individual as a fingerprint is, as an aid to identification.
Embryo
the earliest stages in the development of a new plant or animal from a fertilized ovum and entirely dependent on nutrients supplied by the parent.
Gel electrophoresis
the separation of nucleic acids or proteins on the basis of their size and electrical charge by measuring their rate of movement through a gel.
Genetic modification
the change to the genetic constitution of an organism by artificial methods.
Polymerase chain reaction (PCR)
a technique for amplifying DNA in vitro by incubating it with primers, DNA polymerase, and nucleotides.
Plasmid
the DNA of prokaryote in the circular chromosome.
Restriction endonucleases
an enzyme that cuts DNA at specific sites, producing small fragments used in genetic engineering.
Somatic cell
all body cells except sex cells (cells producing gametes).
Abiotic factors
the non-living physical and chemical attributes of a system, for example light or temperature in an environment.
Autotroph
an organism that uses solar energy or chemical energy to manufacture the organic compounds it needs as nutrients from simple inorganic compounds obtained from its environment.
Biotic factors
attributes in an ecosystem that refer to living organisms.
Chi-squared test
a statistical test of the fit between a theoretical frequency distribution and a frequency distribution of observed data for which each observation may fall into one of several classes.
Community
formed by populations of different species living together and interacting with each other.
Consumers
heterotrophs that feed on living organisms by ingestion.
Crossbreeding
when members of different species breed together.
Detritivores
heterotrophs that obtain organic nutrients from dead organisms by internal digestion.
Ecosystem
community of different species interacting with each other and with the chemical and physical factors making up the non-living environment.
Heterotroph
an organism that gets its organic nutrients by feeding on autotrophs or other heterotrophs.
Inorganic nutrients
chemical elements, compounds, and other substances necessary to sustain life processes that are not chemically carbon-based.
Interbreeding
when two members of the same species mate and produce offspring.
Mesocosm
an experimental tool that brings a small part of the natural environment under controlled conditions.
Population
a group of organisms of the same species who live in the same area at the same time.
Quadrat sampling
square or rectangular plot of land, a quadrat, marked off at random to isolate a sample and determine the percentage of vegetation and animals occurring within the marked area.
Random numbers
a number chosen by a random sampling from a table or generated by a computer.
Saprotrophs
heterotrophs that obtain organic nutrients from detritus by external digestion.
Species
groups of organisms that can potentially interbreed to produce fertile offspring.
Sustainable communities
communities that are capable of being maintained at a steady level without exhausting natural resources or causing severe ecological damage.
Autotroph (or producer)
an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.
Biomass
the total mass of living matter within a given unit of environmental area, expressed in terms of living or dry weight per unit area.
Cell respiration
a series of metabolic processes that take place within a cell in which biochemical energy is produced from organic substances and stored as energy carriers (ATP) for use in the energy-requiring activities of the cell.
Chemical energy
energy released from a substance, or absorbed in the formation of a chemical compound, during a chemical reaction.
Ecosystem
a system that includes all biotic factors (living organisms) in an area as well as its abiotic factors (physical environment) functioning together as a unit.
Energy flow
the movement of energy around an ecosystem by biotic and abiotic means.
First consumer
the name given to an organism that feeds on the producer in a food chain. For example, a goat is considered a first order consumer since it eats green plants.
Food chains
a feeding hierarchy in which organisms in an ecosystem are grouped into trophic (nutritional) levels and are shown in a succession to represent the flow of food energy and the feeding relationships between them.
Heterotroph
an organism that obtains carbon by feeding on the organic material present in other organisms, living or dead.
Light energy
the energy produced or given off directly from the sun causing the growth of plants and the existence of most life forms.
Photosynthesis
the process in green plants and certain other organisms by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source.
Producer (or autotroph)
an organism that is able to form nutritional organic substances from simple inorganic substances such as carbon dioxide.
Pyramids of energy
a graphical model to show how the energy flows through a food chain, how the amount of energy is decreasing and becoming less available for organisms as it enters each trophic level, and how much of the energy in the ecosystem is lost to the atmosphere as heat.
Secondary consumer
an organism that feeds on primary consumers.
Trophic level
the position in a food chain occupied by a group of organisms with similar feeding modes.
Anaerobic organisms
occur in the absence of oxygen or do not require oxygen to live. For example, anaerobic bacteria produce energy from food molecules without the presence of oxygen.
Autotrophs organisms
that use solar energy or chemical energy to manufacture the organic compounds they need as nutrients from simple inorganic compounds obtained from their environment.
Biomass
the total mass of living matter within a given unit of environmental area.
Carbohydrates
any of a large group of organic compounds, including sugars and polysaccharides, such as cellulose, glycogen, and starch, that contain carbon, hydrogen, and oxygen, with the general formula (CH2O)n. They are an important source of food and energy for animals.
Carbon dioxide (CO2)
a colourless, odourless, incombustible gas present in the atmosphere and formed during respiration, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates.
Carbon flux
the flow of carbon from one carbon pool to another.
Cell respiration
a series of metabolic processes that take place within a cell in which biochemical energy is produced from organic substances and stored in ATP for use in the energy-requiring activities of the cell.
Fossilised organic matter
when remains of organisms of a past geologic age have been preserved in a fossil form.
Gigatone
equivalent to a one billion tonnes.
Limestone
a sedimentary rock consisting mainly of calcium carbonate, deposited as the calcareous remains of marine animals or chemically precipitated from the sea.
Methane (CH4)
an odourless, colourless, flammable gas. It is the major constituent of natural gas, which is used as a fuel, and is an important source of hydrogen and a wide variety of organic compounds.
Peat
a compact, brownish deposit of partially decomposed vegetable matter saturated with water, it found in uplands and bogs in temperate and cold regions and used as a fuel.
Waterlogged soil
a soil that is soaked or saturated with water.
Aerosol
a collection of tiny solid or liquid particles in the atmosphere that can come from natural sources (such as wildfires) or people's activities (such as burning fossil fuels). Some aerosols make the atmosphere warmer because they absorb energy. Others have a cooling effect because they reflect sunlight back into space.
Biofuel
a type of fuel produced from plants or other forms of biomass. Examples of biofuels include ethanol, biodiesel, and biogas.
Biomass
material that comes from living things, including trees, crops, grasses, and animals and animal waste. Some kinds of biomass, such as wood and biofuels, can be burned to produce energy.
Carbon dioxide (CO2)
a colourless, odourless greenhouse gas produced naturally when dead animals or plants decay. It is used by plants during photosynthesis. People are adding carbon dioxide into the atmosphere, mostly by burning fossil fuels.
Climate change
a significant change in the Earth's climate, including changes in weather patterns, the oceans, ice and snow, and ecosystems around the world.
Climate
the average weather conditions in a particular location or region at a particular time of the year. Climate is usually measured over a period of 30 years or more.
Coral reef
a marine ridge or reef consisting of coral and other organic material consolidated into limestone.
Fossil fuel
a type of fuel created over millions of years as dead plant and animal material becomes trapped and buried in layers of rock, and then heat and pressure transform this material into a fuel deep within the Earth. Examples of fossil fuels include coal, oil, and natural gas.
Global warming
the increase in temperature near the surface of the Earth as a result of natural causes. However, the term is most often used to refer to recent and on-going warming caused by people's activities.
Greenhouse gases
natural or man-made gases that trap heat in the atmosphere and contribute to the greenhouse effect. Greenhouse gases include water vapour, carbon dioxide, methane, nitrous oxide, and fluorinated gases.
Infrared radiation
a type of electromagnetic radiation. The Earth gives off energy in the form of infrared radiation, which is not visible to the naked eye and feels like heat to the human body.
Long wave radiation (infrared light)
radiation emitted in the spectral wavelength greater than 4 µm corresponding to the radiation emitted from the Earth and atmosphere.
Methane (CH4)
a colourless, odourless greenhouse gas that occurs both naturally and as a result of people's activities. Methane is produced by the decay of plants, animals, and waste, as well as other processes.
Nitrous oxide (NOx)
a colourless, odourless greenhouse gas that occurs both naturally and as a result of people's activities. Major sources include farming practices (such as using fertilizers) that add extra nitrogen to the soil, burning fossil fuels, and certain industrial processes.
Ozone (O3)
a gas made up of three atoms of oxygen bonded together. High in the atmosphere, ozone naturally shields the Earth from harmful ultraviolet radiation and closer to the Earth's surface is a pollutant that is formed by other pollutants that react with each other. Ozone is also a greenhouse gas.
Radiation
energy that travels in the form of a particle or a wave and exists in many different forms, such as electromagnetic radiation, X-rays, ultraviolet radiation, infrared radiation, and visible light.
Ultraviolet (UV) radiation
a type of electromagnetic radiation, not visible to the naked eye that is produced by the sun. Most UV radiation is blocked by ozone high in the Earth's atmosphere, but some of it reaches the Earth's surface and can lead to skin cancer and eye damage.
Water vapour (H2O)
water that is present in the atmosphere as a gas, and as a greenhouse gas it plays an important role in the natural greenhouse effect.
Adaptive radiation
the diversification of several new species from a recent ancestral source, each adapted to utilize or occupy a vacant adaptive zone.
Artificial selection
the human intervention in animal or plant reproduction to ensure that certain desirable traits are represented in successive generations.
Continuous variation
the variation in phenotypic traits, such as body weight or height, in which a series of types are distributed on a continuum rather than grouped into discrete categories.
Discontinuous variation
the variation in phenotypic traits in which types are grouped into discrete categories with few or no intermediate phenotypes.
Evolution
the change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
Fossil
a remnant, or representation, of an organism that existed in a past geological age, or of the activity of such an organism, occurring in the form of mineralized bones, shells, etc., as casts, impressions, and moulds.
Divergent evolution
the change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
Heritable characteristics
characteristics that are capable of being passed from one generation to the next through the genes.
Homologous structures
structures derived from a common ancestor or same evolutionary or developmental origin but not necessarily in function: the wing of a bird and the foreleg of a horse are homologous.
Melanism
an increased amount of black or nearly black pigmentation (as of skin, feathers, or hair) of an organism, resulting from the presence of melanin.
Pentadactyl limb
a limb with five digits, such as a human hand or foot, which is found in many amphibia, reptiles, birds, and animals, which can allow us to deduce that all species in these categories derived from one common ancestor.
Population
a group of organisms of one species that interbreed and live in the same place at the same time (e.g. deer population).
Selective breeding
the intentional breeding of organisms with desirable traits in an attempt to produce offspring with similar desirable characteristics or with improved traits.
Species
an individual belonging to a group of organisms (or the entire group itself) having common characteristics and been capable of mating with one another to produce fertile offspring.
Adaptations
a feature of an organism that favours its survival to reproductive age. Adaptations can be behavioural, physiological, or structural.
Antibiotic
a chemical produced by microbes to kill off competing microbes.
Meiosis
reduction division involving the production of gametes.
Mutation
a change in DNA.
Natural selection
survival to reproductive age of the varieties that are best adapted to existing environmental conditions.
Selection pressure
an environmental variable that acts to remove poorly adapted individuals.
Sexual reproduction
reproduction involving the union of gametes.
Species
a naturally interbreeding group of organisms with similar morphology.
Variation
the range of phenotypes within a population.
Archaeans
one of the prokaryotic domains of life. They tend to live in extreme environments, they have RNA polymerases and ribosomes that are closer to eukaryotes.
Bacteria
one of the prokaryotic domains of life, more diverse than archaeans.
Binomial nomenclature
agreed upon system for naming organisms consisting of genus and species.
Class
a subdivision of a phylum, a class is composed of one or more orders of organism.
Domains
one of the three major categories of life: archaea, bacteria, and eukarya.
Eukaryotes
one of the three domains of life, cells are compartmentalized.
Family
a subdivision of an order: composed of one or more genera.
Genus
a subdivision of a family: composed of one or more species.
Kingdom
a taxonomic group that contains one or more phyla.
Order
a subdivision of a class, composed of one or more families of organism.
Phylum
a subdivision of a kingdom, composed of one or more classes of organism.
Species
a group of related organisms that can successfully interbreed in the wild.
Taxon
a group of species which shares and evolutionary relationship.
Taxonomy
the science of classification.
Viruses
non-living biological entities that have infectious properties - non-living pathogens.
Analogous
trait structures which are similar because of convergent evolution.
Clade
a group comprised of an ancestral species plus all of the species that have evolved from the organism.
Cladistics
constructing a phylogenetic tree based on primitive and shared derived characteristics.
Cladograms
a diagram which shows groupings based on primitive and shared derived characteristics.
Convergent evolution
where species from different lineages show similar characteristics because they are subject to similar selection pressures.
Divergent evolution
a pattern of evolution where an ancestral species evolves into a number of distinct species due to exposure of different populations to different selection pressures.
Figwort
a family of angiosperms.
Homologous trait
Traits that are shared by species with a common ancestor. These traits are similar in structure, but may have very different functions and appearances.
Molecular clock
using the number of differences in DNA or amino acid sequences to deduce how long ago species split.
Absorption
the movement of a substance, such as a liquid or solute, across a cell membrane by means of diffusion, osmosis, or active transport.
Amylase
an enzyme, found mainly in saliva and pancreatic fluid, that converts starch and glycogen into simple sugars.
Cellulose
a complex carbohydrate that is composed of glucose units, and forms the main constituent of the cell wall in most plants.
Circular muscles
the inner layer of smooth (involuntary) muscle of the muscle coat (muscularis externa) of the small intestine in which the muscle fibres encircle the lumen.
Dialysis
the separation of smaller molecules from larger molecules, or of dissolved substances in a solution by selective diffusion through a semi-permeable membrane,
Endopeptidase
any of a large group of enzymes that catalyse the hydrolysis of peptide bonds in the interior of a polypeptide chain or protein molecule.
Enzymes
proteins or conjugated proteins produced by living organisms and functioning as biochemical catalysts.
Epithelium
the thin tissue forming the outer layer of a body's surface and lining the alimentary canal and other hollow structures.
Glycogen
a polysaccharide that is the main form of carbohydrate storage in animals and occurs primarily in the liver and muscle tissue. It is readily converted to glucose when needed by the body to satisfy its energy needs.
Lipase
a pancreatic enzyme that catalyses the breakdown of lipids through the hydrolysis of the linkages between fatty acids and glycerol in triglycerides and phospholipids.
Liver
a large glandular organ located in the upper right side of the abdominal cavity active in the secretion of bile and various metabolic processes.
Longitudinal muscles (of the stomach)
the outer longitudinal layer of smooth muscles, continuous with that of the esophagus.
Lumen
the inner open space or cavity of the small intestine.
Macromolecule
a very large molecule, such as a polymer or protein, consisting of many smaller structural units linked together.
Mineral ions
individual elements with an electrical charge.
Monomer
a molecule that can combine with others to form a polymer.
Mucosa
a mucus-secreting membrane lining all bodily passages that are open to the air, such as the digestive tract.
Nucleic acids
complex compounds found in all living cells composed of bases, carbohydrates, and phosphoric acid. Nucleic acids in the form of DNA and RNA control cellular function and heredity.
Pancreas
a gland in vertebrates, lying behind the stomach, that secretes pancreatic juice into the duodenum and insulin and glucagon into the bloodstream.
Small intestine
the narrow, winding, upper part of the intestine where digestion is completed and nutrients are absorbed by the blood.
Starch
a polysaccharide composed of glucose units that occurs widely in plant tissues in the form of storage.
Villus (plural villi)
one of the minute finger-shaped processes of the mucous membrane of the small intestine that serve in the absorption of nutrients.
Vitamin
any of various fat-soluble or water-soluble organic substances essential in minute amounts for normal growth and activity of the body and obtained naturally from plant and animal foods.
Aorta
the main artery of circulatory system that carries blood from the left side of the heart to the arteries of all limbs and organs except the lungs.
Arteriole
a small terminal branch of an artery that connects with a capillary.
Artery
a vessel that carries blood away from the heart to organs through the body.
Atrium (plural atria)
a chamber that receives blood returning to the heart.
Blood pressure
the hydrostatic force that blood exerts against the wall of a blood vessel.
Capillary
a microscopic blood vessel that penetrates the tissues and consists of a single layer of endothelial cells to allow exchange with interstitial fluid.
Cardiac output
the volume of blood pumped per minute by the left ventricle of the heart.
Diastolic pressure
the minimum blood pressure during relaxation of heart muscles.
Elastic fibres
a thick, yellow connective-tissue fibre composed principally of elastin and characterized by giving great elasticity to tissues in the body.
Epinephrine
a hormone produced as a response to stress, also called adrenaline.
Medulla
the lowest part of the brain that controls autonomic and homeostatic functions.
Myogenic contraction
a contraction of the heart without external stimulation from a nerve.
Pacemaker
a specialized region of the right atrium that sets the rate of heart contraction, also called the sinoatrial (SA) node.
Pulmonary circulation
the separated circulatory system that links the lungs and heart in humans.
Pulse
the force of blood leaving the heart in one heartbeat; it is felt where arteries pass near the skin.
Systemic circulation
the separated circulatory system that links the heart to the rest of the body.
Systolic pressure
the maximum blood pressure caused by heart muscles contracting and pumping blood.
Valve
a membranous structure in a hollow organ or passage that folds or closes to prevent the return flow of the body fluid passing through it.
Vasoconstriction
when the circular muscles in the artery wall contract, narrowing the lumen.
Vasodilation
when the circular muscles relax, increasing the lumen size and hence blood flow to downstream tissues.
Vein
a vessel that returns blood to the heart.
Ventricles
the chambers on the left and right side of the heart that receive blood from the atria and contract to force it into the aorta and pulmonary artery respectively.
AIDS (Acquired immunodeficiency syndrome)
the name of the active HIV infection characterized by the reduction of T-cells and the appearance of characteristic secondary infections.
Antibiotic
a chemical that kills or inhibits growth of bacteria by deregulation of metabolic pathways.
Antibody
an antigen-binding protein produced by B-cells.
Blood clotting
the process by which blood becomes thick and stops flowing, forming a solid cover over any place where your skin has been cut or broken.
Clotting factors
proteins in the plasma that serve to activate various parts of the blood clotting process by being transformed from inactive to active forms. Also known as coagulation factors.
Fibrin
the activated form of the blood-clotting protein fibrinogen.
Fibrinogen
a protein in the blood plasma that is essential for the coagulation of blood and is converted to fibrin by the action of thrombin.
Gene
a section of DNA on a chromosome that controls a specific trait.
Lymphocyte
a white blood cell that could be a B-cell or a T-cell.
Metabolism
the totality of all the chemical processes in an organism, consisting of anabolic and catabolic mechanisms.
Memory cell
a long-lived cell of the immune system that has previously encountered a specific antigen and that upon re-exposure produces large amounts of antibody.
Mucous membranes
membrane lining all body passages and having cells and associated glands that secrete mucus. Also called mucosa.
Pathogen
any organism that causes disease, such as a bacterium or fungus.
Penicillin
any of the antibiotic drugs obtained from penicillium moulds or produced synthetically, most active against gram-positive bacteria and used in the treatment of various infections and diseases.
Phagocytic white blood cells
a type of white cell that carries endocytosis of large foreign substances.
Plasma cell
any of the antibody-producing cells, and derived from B-cells. It plays a major role in antibody-mediated immunity reacting with a specific antigen.
Platelet
a small fragment of red blood cells found in the blood plasma that functions to promote blood clotting.
Thrombin
a protease in blood that facilitates blood clotting by converting fibrinogen to fibrin.
Thrombus
a clot formed in the coronary arteries.
Alveolus (plural alveoli)
air sac that constitutes the gas exchange surface of the lungs.
Antagonistic muscle
a muscle that opposes the action of another.
Bronchi
the two main branches of the trachea that go into the lungs; this then further divides into the bronchioles and alveoli.
Bronchioles
any of the fine, thin-walled, tubular extensions of a bronchus.
Capillary
one of the minute blood vessels that connect arterioles and veins where the interchange of various substances occur.
Concentration gradient
the gradient resulting from an unequal distribution of ions across the cell membrane.
Diaphragm
a dome-shaped muscular partition separating the thorax from the abdomen. It plays a major role in breathing as its contraction increases the volume of the thorax and so inflates the lungs.
Emphysema
a chronic respiratory disease where there is over-inflation of the air sacs (alveoli) in the lungs causing a decrease in lung function and often breathlessness.
Epidemiology
the study of the incidence and causes of disease.
Expiration
when the muscles of the thorax contract to cause the volume to decrease, this increases the pressure in the lungs and air moves from the higher pressure inside the lungs to the lower pressure outside the body.
Inspiration
when the air moves from a higher pressure (outside the body) to the lower pressure (inside the lungs).
Intercostal muscles
muscles found between the ribs. They are mainly involved in the mechanical aspect of breathing.
Pneumocyte
one of the cells lining the alveoli (the air sacs) in the lung that assists in gas exchange and in the secretion of pulmonary surfactant.
Spirometer
an instrument for measuring the volume of air entering and leaving the lungs.
Surface tension
the force that causes the molecules on the surface of a liquid to be pushed together and form a layer.
Surfactant
a substance composed of lipoprotein that is secreted by the alveolar cells of the lung and serves to maintain the stability of pulmonary tissue by reducing the surface tension of fluids that coat the lung.
Tidal volume
the volume of air inspired or expired in a single breath during regular breathing.
Trachea
thin-walled, cartilaginous tube descending from the larynx to the bronchi and carrying air to the lungs.
Ventilation rate
the volume of air passing into and out of the lungs per minute.
Acetylcholine
a molecule released by neurons at the neuromuscular junction that causes muscle contraction.
Action potential
a localized change in electrical potential, from about -70 mV to +30 mV and back again, that occurs across a nerve fibre during transmission of a nerve impulse.
Axon of neurons
the long thread-like extension of a nerve cell that conducts nerve impulses from the cell body.
Cholinergic synapse
a junction between two cells that employs acetylcholine as its transmitter substance.
Depolarization
a positive-going change in the membrane potential of neurons making it more positive, or less negative. It may result in an action potential.
Myelination
the process of development or formation of a myelin sheath around a nerve fibre.
Neuron
a specialized, impulse-conducting cell that is the functional unit of the nervous system, consisting of the cell body and its processes, the axon, and dendrites.
Neurotransmitter
a substance that transmits nerve impulses across a synapse.
Oscilloscope
an electronic instrument used to observe and measure changing electrical signals.
Presynaptic neuron
a neuron from which an electrical impulse is transmitted across a synaptic cleft to a postsynaptic neuron by the release of a chemical neurotransmitter.
Refractory period
the delay after repolarization where the resting potential is restored.
Repolarization
the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential.
Resting potential
the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse.
Saltatory conduction
the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.
Synapses
the junction between two nerve cells, consisting of a minute gap across which impulses pass by neurotransmitters.
Threshold potential
the critical level to which the membrane potential must be depolarized in order to initiate an action potential.
Adipose tissue
a type of connective tissue that contains stored cellular fat.
Alpha cells (_-cells)
endocrine cells in the pancreas that synthesize and secrete glucagon, which elevates the glucose levels in the blood.
Beta cells (_-cells)
cells in the pancreas that make insulin, a hormone that controls the level of glucose (a type of sugar) in the blood.
Blood glucose
the concentration of glucose in the blood, measured in milligrams of glucose per 100 ml of blood. Normal adult blood glucose levels range from 70 to 115 mg/100 ml.
Circadian rhythm
a physiological cycle of about 24 hours present in eukaryotic organisms that persists even in the absence of external cues.
Diabetes
a group of metabolic diseases in which a person has high blood sugar, either because the pancreas does not produce enough insulin, or because cells do not respond to the insulin that is produced.
Embryo
an organism in its early stages of development, especially before it has reached a distinctively recognizable form.
Embryonic gonads
the male and female sex organs in the embryo.
Estrogen
a female steroid hormone produced by the ovaries and responsible for promoting and maintenance of female secondary sex characteristics.
Gamete
a reproductive cell or sex cell that contains the haploid set of chromosomes, e.g. sperm cell (male reproductive cell) and egg cell (female reproductive cell).
Glucagon
a hormone secreted by the pancreas that raises blood glucose levels by hydrolysing glucagon molecules in the liver.
Hormone
a substance, usually a peptide or steroid, produced by one tissue and transported by the blood to another to affect physiological activity, such as growth or metabolism.
Hypothalamus
a region of the brain that functions as the main control centre for the autonomic nervous system.
Insulin
a hormone that lowers blood glucose levels by promoting the uptake of glucose by most body cells and the storage in the liver.
Leptin
an adipose-derived hormone that plays a key role in regulating energy intake and expenditure, including appetite and hunger, metabolism, and behaviour.
Melatonin
a hormone derived from serotonin that plays a role in sleep, ageing, and reproduction in mammals.
Menstrual cycle
the monthly series of physiological changes in women that occurs in the uterus and ovary for the purpose of sexual reproduction. If the egg is not fertilized, the lining of the uterus breaks down and is discharged during menstruation.
Metabolic rate
the chemical processes occurring within a living cell or organism during a certain period.
Negative feedback
when the system responds in an opposite direction to a perturbation.
Pancreas
a long, irregularly-shaped gland in vertebrates that secretes pancreatic juice into the small intestine and insulin and glucagon into the bloodstream.
Pineal gland
a small, cone-shaped organ in the brain that secretes the hormone melatonin.
Pituitary gland
an endocrine gland that secretes nine hormones that regulate homeostasis.
Positive feedback
feedback in which the system responds to a perturbation in the same direction as the perturbation.
Progesterone
a steroid hormone secreted by the corpus luteum of the ovary and the placenta that acts to prepare the uterus for implantation of the fertilized ovum, to maintain pregnancy, and to promote development of the mammary glands.
Testosterone
a steroid hormone and the principal male sex hormone.
Thyroid gland
an endocrine gland at the base of the neck that makes and stores hormones that help regulate the rates of metabolism, growth, and development.
Thyroxin
an iodine-containing hormone produced by the thyroid gland, that increases the rate of cell metabolism and regulates growth, and that is made synthetically for treatment of thyroid disorders.
Base sequencing
the procedure of determining the order of nucleotides in a DNA section.
DNA gyrase
a bacterial enzyme that catalyses the breaking and re-joining of bonds linking adjacent nucleotides in circular DNA to generate supercoiled DNA helices.
DNA polymerases
various enzymes that function in the replication and repair of DNA by catalysing the linking of nucleotides in a specific order, using single-stranded DNA as a template.
DNA primase
an enzyme involved in the initiation of DNA replication that catalyses the polymerization of short RNA primers on the template DNA.
DNA profiling
the analysis of a small amount of genetic material used to identify multilocus DNA banding patterns that are specific to an individual is often used to provide evidence in criminal law cases; also called genetic fingerprinting.
DNA replication
the process of making an identical copy of a DNA molecule, using existing DNA as a template for the synthesis of new DNA strands.
Helicase
a prokaryote enzyme that unwinds the DNA helix at the replication fork, breaking the hydrogen bonds, to allow the resulting single strands to be copied.
Histone
any of several small, basic proteins most commonly found in association with the DNA in the chromatin of eukaryotes.
Intron
a segment of a gene situated between exons that is removed before the translation of messenger RNA and does not function in coding for protein synthesis.
Lagging strand
the strand of the DNA double helix that, because of its orientation that is opposite to the working orientation of DNA polymerase III, is synthesized in a series of short fragments known as Okazaki fragments.
Leading strand
DNA strand being replicated by continuous polymerization at the 3_ growing tip.
Nucleosome
the basic bead-like unit of DNA packing in eukaryotes, consisting of a sequence of DNA wound around a protein core composed of eight histones.
Nucleotides
the building blocks of a nucleic acid, consisting of a carbon sugar covalently bonded to a nitrogenous base and a phosphate group.
Primer
a segment of DNA or RNA that is complementary to a given DNA sequence and that is needed to initiate replication by DNA polymerase.
Replication fork
a site on a DNA molecule at which the unwinding of the helices and synthesis of daughter molecules are both occurring during DNA replication.
Tandem repeats
copies of genes repeated one after another along a chromosome.
Telomere
a region of repetitive nucleotide sequences at each end of a chromatid that is involved in the replication and stability of DNA molecules protecting the end of the chromosome from deterioration.
X-ray diffraction
an analytical method in which X-rays change direction on contact with matter, resulting in changes in radiation intensity, that is used to determine the three-dimensional arrangement of atoms.
5' to 3' direction
the only direction that DNA polymerase can synthesize DNA; it does so by adding nucleotides to the 3' end of a DNA strand.
DNA methylation
the modification of a strand of DNA after it is replicated, in which a methyl (CH3) group is added and is one of the methods used to regulate the expression of genes.
Exon
sequence of DNA that codes information for protein synthesis that is transcribed to messenger RNA.
Gene expression
conversion of the information from the gene into mRNA via transcription and then to protein via translation resulting in the phenotypic manifestation of the gene.
Genome
total genetic contents of an organism.
Intron
segment of a gene situated between exons that is removed before the translation of messenger RNA and does not function in coding for protein synthesis.
Non-coding DNA
components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules while others are not transcribed.
Nucleosome
structural unit of a eukaryotic chromosome, consisting of a length of DNA coiled around a core of histones.
Promoter
site in a DNA molecule at which RNA polymerase and transcription factors bind to initiate transcription of mRNA.
Repressor
substance that binds to the operator and obstructs the RNA polymerase from binding to the promoter and transcribing the gene.
Splicing of mRNA
removal of introns from a primary transcript and the subsequent joining of exons in the production of a mature RNA molecule.
Terminator
sequence of nucleotides that signals the end of transcription or translation and the completion of the synthesis of a nucleic acid or protein molecule.
Transcription
process by which messenger RNA is synthesized from a DNA template resulting in the transfer of genetic information from the DNA molecule to the messenger RNA.
Alpha helix
a coiled conformation common in many proteins; it is characterized by a spiral chain of amino acids stabilized by hydrogen bonds in which the resulting structure resembles a spring or helix.
Beta pleated sheet
a structure that occurs in many proteins and consists of two or more parallel adjacent polypeptide chains arranged in a zigzag pattern, so that hydrogen bonds can form between the chains.
Bound ribosomes
ribosomes that are attached to the outer surfaces of endoplasmic reticulum and produce proteins that are used within the plasma membrane or are expelled from the cell via exocytosis.
Conjugated protein
a biochemical compound, such as hemoglobin, made up of a protein molecule and a non-protein prosthetic group.
Different conformations
alternative structures of the same protein.
Electron micrograph
a photograph or image of a specimen taken using an electron microscope.
Free ribosomes
can move about anywhere in the cytoplasm and the proteins they make are free to go anywhere within the cell.
Non-polar amino acid
an alpha-amino acid in which the functional group (R-) attached to the alpha-carbon has hydrophobic properties.
Polar amino acid
an alpha-amino acid in which the functional group (R-) attached to the alpha-carbon has hydrophilic properties.
Polypeptide
a polymer of amino acids joined together by peptide bonds.
Polysome
a group of ribosomes joined by a molecule of messenger RNA containing the genetic information code that is to be translated during protein synthesis.
Primary structure
the linear sequence or order of amino acids of a protein; it determines how the protein will fold into a more advanced structure, such as the unique three-dimensional structure of protein.
Prosthetic group
the non-protein component of a conjugated protein, for example the heme group in hemoglobin.
R group
the chemical group attached to the alpha carbon in an amino acid that is different for each of the common 20 amino acids found in proteins.
Quaternary structure
the particular shape of a protein defined by the characteristic three-dimensional arrangement of its constituent polypeptide subunits.
Secondary structure
the repetitive folding of the polypeptide backbone of a protein due to the hydrogen bonds formed between the peptides.
Tertiary structure
the irregular folding of a protein molecule due to the interactions of the R- groups involving hydrophobic interactions, ionic bonds, hydrogen bonds, or disulfide bonds.
Translation
the transfer of information from a RNA molecule into a polypeptide, involving the changing of language from nucleic acid to amino acid.
tRNA
RNA molecules that transport amino acids to ribosomes for incorporation into a polypeptide undergoing synthesis (according to directions coded in the mRNA).
Activation energy
the initial input of energy that is required to trigger a chemical reaction.
Active site
the location on the enzyme where the substrate binds.
Allosteric inhibitor
a molecule that binds at a site away from the active site triggering a conformational change that prevents the binding of substrate.
Bioinformatics
the application of computers to the study of biological information.
Competitive inhibitor
a molecule that binds to the active site of an enzyme and prevents the binding of a substrate.
Metabolism
the sum total of all chemical reactions that occur within an organism.
Metabolic chains
a series of reactions, with each one catalyzed by a different enzyme.
Metabolic cycles
a cycle of enzyme catalyzed reactions that regenerates a series of organic molecules with each turn of the cycle.
Non-competitive inhibitor
a molecule that binds to an enzyme at a location outside the active site and inhibits the enzyme's function.
Transition state
a state in which all of the original bonds are under maximum strain resulting in an unstable intermediate.
Substrate
the substance that binds to the enzyme at the active site.
Aerobic respiration
a type of respiration where oxygen is consumed.
ATP
a nucleotide triphosphate that is a common source of energy in cells.
ATP synthase
an enzyme that utilizes the H+ electrochemical gradient to synthesize ATP.
Chemiosmosis
a process for making ATP using the energy stored in an electrochemical gradient of hydrogen ions.
Cristae
invaginations of the inner mitochondrial membrane.
Decarboxylation
a chemical reaction that involves the removal of CO2.
Electron tomography
a method used to generate a three-dimensional image of the inner mitochondrial membrane.
Electron transport chain
a group of proteins that accept and donate electrons in a series.
Endergonic
energy storing reactions.
Exergonic
energy releasing reactions.
Glycolysis
a metabolic pathway that breaks glucose down to pyruvate.
Link reaction
a decarboxylation reaction that occurs in the mitochondrion between glycolysis and the Krebs cycle.
Lysis
splitting
Mitochondrial matrix
a compartment inside the inner membrane of the mitochondrion.
Oxidation
the loss of electrons or loss of hydrogen.
Oxidative phosphorylation
the production of ATP through a series of oxidation and reduction reactions.
Phosphorylation
the addition of a phosphate group to a molecule.
Pyruvate
the end product of glycolysis.
Reduced NAD
the energy rich form of the hydrogen carrier.
Reduction
the gain of electrons or gain of hydrogen.
Calvin cycle
the use of ATP and reduced NADP in the stroma to regenerate RuBP and generate carbohydrates in the light independent stage of photosynthesis.
Carbon fixation
the incorporation of inorganic CO2 into an organic molecule.
Chemiosmosis
the process of making ATP using the energy stored in a proton gradient.
Cyclic photophosphorylation
involves photosystem 1 in a pattern of electron flow where ATP is generated.
Light-dependent reactions
the reactions within photosynthesis that use light to generate ATP and reduced NADP.
Light-independent reactions
the photosynthetic reactions that take place within the stroma and use reduced NADP and ATP to generate carbohydrates.
Photoactivation
the production of energetic electrons in reaction centers through the absorption of light.
Photolysis
the splitting of water.
Photophosphorylation
the production of ATP using the energy of sunlight.
Photosystem 1
an integral protein transport system used in the light-dependent reactions - it can carry out cyclic photophosphorylation, and produces reduced NADP.
Photosystem 2
the first photosystem in the light-dependent reactions - it uses electrons from photolysis, and produces ATP.
Proton gradient
a difference in proton concentration on either side of a membrane.
Reduced NADP
produced by photosystem 1, it is an energy source for the Calvin cycle.
Rubisco
an enzyme that fixes CO2 to RuBP in the Calvin cycle.
RuBP
the molecule that reacts with CO2 during carbon fixation.
Stroma
the chemical medium between the inner chloroplast membrane and the thylakoid membrane.
Thylakoid space
the lumen of the thylakoid.
Thylakoid
the membrane that is the site of photosynthesis.
Triose phosphate
an intermediate in the Calvin cycle, also known as glyceraldehyde-3-phosphate.
Adhesive property
the joining of two different substances due to attractive forces that hold them, such as keeping the water drops on the surfaces of leaves.
Capillary tubing
a tube of small internal diameter that holds liquid by capillary action.
Cohesive property
the sticking together of similar molecules, such as one water molecule being attracted to another water molecule. It also causes water molecules to form drops.
Osmosis
net movement of water molecules through a semi-permeable membrane from an area of higher water potential to an area of lower water potential.
Potometer
a device used for measuring the rate of water uptake of a plant due to photosynthesis and transpiration.
Water tension
the force created by evaporation of water coupled with the cohesive and adhesive forces in plants, enough to support a column of water against the forces of gravity in plants and trees.
Transpiration
the loss of water by evaporation in terrestrial plants, especially through the stomata (accompanied by a corresponding water uptake from the roots).
Xylem
the woody tissue which supports and transport water in vascular plants.
Active transport
a transport mechanism where ions or molecules move against a concentration gradient, this movement requires energy.
Hydrostatic pressure gradient
the stress that develops when solutions containing different concentrations of solute in a common solvent are separated by a membrane that is permeable to the solvent, but not the solute.
Incompressibility of water
the incapability of water to lose volume in response to pressure.
Osmosis
the diffusion of fluid through a semi-permeable membrane from a solution with a low solute concentration to a solution with a higher solute concentration until there is an equal concentration of fluid on both sides of the membrane.
Phloem
the food-conducting tissue of vascular plants that conducts synthesized nutrients to different parts of the plants.
Sieve tubes
an element of phloem tissue consisting of a longitudinal row of thin-walled elongated cells with perforations in their connecting walls through which food materials pass.
Auxin
a plant hormone that causes the elongation of cells in shoots and is involved in regulating plant growth.
Meristem
a region of plant tissue, found chiefly at the growing tips of roots and shoots and in the cambium, consisting of actively dividing cells forming new tissue.
Micropropagation
the propagation of plants by growing plantlets in tissue culture and then planting them out.
Shoot apex
the tip of a shoot, the apical or lateral shoot meristematic dome together with the leaf primordial, from which emerge the leaves and sub-adjacent stem tissue.
Stem
the main body or stalk of a plant or shrub, typically rising above ground, but occasionally subterranean.
Tropisms
the turning or bending movement of an organism or a part of an organism toward or away from an external stimulus, such as light, heat, or gravity.
Fertilization
the action or process of fertilizing an egg or a female animal or plant, involving the fusion of male and female gametes to form a zygote.
Flowering
the process of producing conspicuous flowers.
Mutualistic relationship
an association between organisms of two different species in which each member benefits.
Pollination
the process of transfer of pollen from the anther to the stigma of a plant.
Shoot apex
the tip of a shoot, the apical or lateral shoot meristematic dome together with the leaf primordial, from which emerge the leaves and sub-adjacent stem tissue.
Allergen
any substance, often a protein, that induces an allergy: common allergens include pollen, grasses, dust, and some medications.
Antibody
a Y-shaped protein on the surface of B-cells that is secreted into the blood or lymph in response to an antigenic stimulus, such as a bacterium or virus.
B-cell
a type of lymphocyte that, when stimulated by a particular antigen, differentiates into plasma cells that synthesize the antibodies that circulate in the blood and react with the specific antigens.
Clones (of plasma cells)
differentiated plasma cells that secrete a specific antibody and a clone of memory cells that make the antibody on subsequent encounters.
Histamine
a physiologically active amine found in plant and animal tissue and released from mast cells as part of an allergic reaction in humans. It causes the dilation of capillaries, constriction of bronchial smooth muscle, and decreased blood pressure.
Hybridoma
a cell hybrid produced in vitro by the fusion of a lymphocyte that produces antibodies and a myeloma tumour cell in order to produce a continuous supply of a specific antibody.
Memory cell
a type of lymphocyte that is released as a specific immune response and is stored in case of a second exposure to the same antigen.
Monoclonal antibodies
any of the highly specific antibodies produced in large quantities by the clones of a single hybrid cell that has been formed in the laboratory by the fusion of a B-cell with a tumour cell.
Pathogen
an agent that causes disease or illness in another organism.
Plasma cell
a fully differentiated B-lymphocyte (white blood cell) that produces a single type of antibody.
Smallpox
an acute, highly infectious, often fatal disease caused by a poxvirus. It is characterized by high fever and aches, and is believed to have been eradicated globally by widespread vaccination.
T-lymphocyte
a type of white blood cell that completes maturation in the thymus and that has various roles in the immune system, including the identification of specific foreign antigens in the body and the activation and deactivation of other immune cells.
Vaccine
a preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure that stimulates antibody production or cellular immunity against the pathogen once administered, but is incapable of causing severe infection.
Actin
a protein that forms (together with myosin) the contractile filaments of muscle cells, and is also involved in motion in other types of cell.
Antagonistic muscle
a muscle that opposes the action of another; for example, the biceps and triceps are antagonistic muscles.
Cartilage
a type of flexible connective tissue with an abundance of collagenous fibres that controls muscle contractions.
Cross bridge
forms in the sarcomere when the globular head of a myosin molecule attaches temporarily to an adjacent actin filament.
Exoskeleton
a rigid external covering for the body in some invertebrate animals, especially arthropods.
Joint capsule
a ligamentous sac that surrounds the articular cavity of a freely movable joint. It is attached to the bones, completely encloses the joint, and is composed of an outer fibrous membrane and an inner synovial membrane.
Light band
the zone of thin filaments in the sarcomere that is not superimposed by thick filaments.
Myofibril
a long, cylindrical organelle in striated muscle cells, composed mainly of actin and myosin filaments, that runs from one end of the cell to the other and is organized in repetitive subunits called sarcomeres.
Myosin filament
one of the contractile elements in skeletal, cardiac, and smooth muscle fibres.
Radioactive element
an element subject to spontaneous degeneration of its nucleus accompanied by the emission of alpha particles, beta particles, or gamma rays.
Sarcomeres
the contractile units of a myofibril. Sarcomeres are repeating units, delimited by the Z bands, along the length of the myofibril.
Synovial fluid
the fluid found in joints like the elbow and knee, it is contained within a membrane that lubricates the joint and allows smooth and pain-free movement.
Synovial joint
the most common and movable type of joint, which is characterized by the presence of a layer of cartilage that lines the opposing bony surfaces, as well as a lubricating synovial fluid.
Tropomyosin
a muscle protein that binds to molecules of actin and troponin to regulate the interaction of actin and myosin.
Troponin
a complex of muscle proteins which, when combined with Ca2+, influence tropomyosin to initiate contraction.
Z lines
a thin membrane in a myofibril, seen on longitudinal sections as a dark line in the centre of the band. The distance between Z bands delimits the sarcomeres of striated muscle.
Antidiuretic hormone (ADH)
a hormone released by the pituitary gland that controls the permeability of the walls of the collecting duct in the kidney, preventing the production of dilute urine.
Bowman's capsule
a double-walled membrane around the glomerulus of each nephron of the vertebrate kidney, its main role is to filter to remove organic wastes, excess inorganic salts, and water.
Collecting duct
a non-secretory tubule that receives urine from several nephrons and discharges it into the pelvis of the kidney.
Dehydration
the excessive loss of water from the body, or from an organ or body part, as a result of illness or fluid deprivation.
Distal convoluted tubule
the convoluted portion of the nephron that lies between the loop of Henle and the non-secretory part of the nephron that is concerned especially with the concentration of urine.
Glomerulus
a group of capillaries, situated within a Bowman's capsule in the nephron of the vertebrate kidney, which filter waste products from the blood and so initiate urine formation.
Haemodialysis
a method used after kidney failure for the removal of certain elements from the blood based on the difference in their rates of diffusion through a semi-permeable membrane while being circulated outside the body. The process involves both diffusion and ultrafiltration.
Loop of Henle
the U-shaped section of the nephron of a vertebrate kidney that is situated between the proximal and distal convoluted tubules and plays a role in the regulation of the concentrating of ions in the urine.
Malpighian tubule system
the organ of excretion in insects and many other arthropods consisting of narrow tubules opening into the anterior part of the hindgut.
Medulla
the inner, darker portion of the parenchyma of the kidneys that consists of the renal pyramids.
Nephron
the structural and functional units of the kidney, numbering about a million in the renal parenchyma, each one is capable of forming urine.
Osmoconformers
marine animals which, in contrast to osmoregulators, maintain the osmolarity of their body fluids such that it is always equal to the surrounding seawater.
Osmoregulator
a body mechanism concerned with the maintenance of constant osmotic pressure relationships.
Proximal convoluted tubule
the convoluted portion of the vertebrate nephron that lies between the Bowman's capsule and the loop of Henle and functions especially in the reabsorption of sugar, sodium and chloride ions, and water from the glomerular filtrate.
Ultra sound treatment
the application of ultrafrequency sound waves to tissues in order to promote healing, break down substances, and reduce pain and swelling.
Ultrafiltration
a high pressure filtration through a semi-permeable membrane in which colloidal particles are retained, while the small sized solutes and the solvent are forced to move across the membrane by hydrostatic pressure forces.
Acrosome reaction
a necessary and irreversible step in fertilization, which is triggered by sperm receptor, in which the sperm's and ovum's membranes fuse and the sperm penetrates the zona pellucida.
Blastocyst
a thin-walled hollow structure in early embryonic development that contains a cluster of cells, called the inner cell mass, from which the embryo arises.
Cortical reaction
a reaction that occurs during fertilization, when the sperm cell unites with the egg's plasma membrane, that prevents entry of a second sperm.
Differentiation
the process regulated by different gene expression by which cells or tissues undergo a change toward a more specialized form or function, especially during embryonic development.
Endometrium
the mucous membrane lining the womb, which thickens during the menstrual cycle in preparation for possible implantation of an embryo.
Estrogen
any of several steroid hormones produced chiefly by the ovaries and responsible for promoting oestrus and the development and maintenance of female secondary sex characteristics.
External fertilization
a form of fertilization in which a sperm cell is united with an egg cell external to the bodies of the reproducing individuals.
Gamete
a mature haploid male or female germ cell, which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Gametogenesis
the process in which cells undergo meiosis to form gametes.
Human chorionic gonadotropin (HCG)
a hormone produced by the placenta that maintains the corpus luteum during pregnancy.
Internal fertilization
when fertilization takes place inside the female body.
Meiosis
the process of cell division in sexually reproducing organisms that reduces the number of chromosomes in reproductive cells from diploid to haploid, leading to the production of gametes in animals and spores in plants.
Mitosis
a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, it is typical of ordinary tissue growth.
Oogenesis
the process of formation of female gametes.
Oxytocin
a hormone released by the pituitary gland that causes increased contraction of the womb during labour.
Placenta
a flattened circular organ in the uterus of pregnant eutherian mammals, nourishing and maintaining the foetus through the umbilical cord.
Polyspermy
an egg that has been fertilized by more than one sperm.
Progesterone
a steroid hormone secreted by the corpus luteum of the ovary and by the placenta that acts to prepare the uterus for implantation of the fertilized ovum and maintains pregnancy.
Seminiferous tubules
any of the numerous long convoluted tubules in the testes which are the sites where spermatozoa mature.
Spermatogenesis
the production or development of mature spermatozoa.
Commensalism
An ecological relationship between species in which one is benefited but the other is little affected.
Competition
An interaction between individuals of the same species or different species whereby resources used by one are made unavailable to others.
Competitive exclusion principle
Principle stating that no two species competing for the same resource can coexist indefinitely.
Coral
Marine invertebrates in the class Anthozoa (phylum Cnidaria). They typically live in compact colonies of identical individual polyps. The group includes the important reef builders that secrete calcium carbonate to form a hard skeleton.
Ecological niche
The ecological role and space that an organism fills in an ecosystem.
Fundamental niche
The full range of environmental conditions and resources an organism can possibly occupy and use (when limiting factors are absent in its habitat).
Intraspecific interactions
Interplay between members of the same species that affects one or more of them.
Interspecific interactions
Interplay between species that affects one or more of them.
Keystone species
Species that have effects on communities that far exceed their abundance.
Limits of tolerance
The highest/lowest values of abiotic factor that an organism can survive.
Parasitism
Situation in which an individual organism, the parasite, consumes nutrients from another organism, its host, resulting in a decrease in fitness to the host as a result of the interaction.
Realized niche
The part of fundamental niche that an organism occupies as a result of presence of limiting factors in its habitat.
Spatial habitat
The physical environment (i.e., the chemical resources and physical conditions) of an organism or organisms.
Symbiosis
Literally "living together," a close association between two or more species.
Transect
A line or path along which the occurrences of studied organisms are recorded.
Zone of stress
The range of values of an abiotic factor that an organism can survive but are not optimal.
Zooxanthellae
Endosymbiotic algae that inhabit the endoderm of tropical cnidarians such as corals, sea anemones, and jellyfish.
Biome
Regions of similar climate and dominant plant types (i.e. a type of ecosystem).
Climax community
A community composed of species that represents the final stage of colonization of a habitat.
Climograph
A graphical representation of basic climatic parameters (e.g. monthly average temperature and precipitation) at a certain location.
Desert
A dry ecosystem characterised by little rainfall, extreme temperatures, and sparse vegetation.
Ecological succession
describes the process by which a sequence of increasingly complex communities develop over time.
Food conversion ratio
is a measure of an animal's efficiency in converting feed mass into the mass of desired output.
Food web
A diagram showing feeding relationships of organisms within an ecosystem or community. It consists of multiple interlinked food chains.
Gersmehl diagrams
Diagrams showing the inter-relationships between nutrient stores and flows in an ecosystem.
Gross production
The amount of organic matter (biomass) produced by plants, expressed as energy per unit area per unit time period.
Net production
The amount of organic matter produced by plants minus what is needed for plant respiration, expressed as energy per unit area per unit time period.
Primary succession
Ecological succession on entirely new land without any established soil (due events such as s volcanic eruptions or glacier retreat).
Secondary succession
Occurs when succession starts on existing soil following a natural or artificial disturbance.
Tagia
Moist subartic forest ecosystem dominated by conifer trees.
Tropical rainforest
A forest ecosystem with high rate of precipitation and high humidity, usually located near the equator.
Alien species
A species living outside its native distributional range or ecosystem.
Bioaccumulation
The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism.
Biological control
A method of controlling pests using other living organisms. It relies on predation, parasitism, herbivory, or other natural mechanisms to control the population of the pest species.
Biomagnification
The process, in an ecosystem, in which a higher concentration of a substance in an organism is obtained higher up the food chain.
Endemic species
A species unique to a defined geographic location or ecosystem.
Gyres
A large system of rotating ocean currents, there are five major rotating currents in the Earth's oceans.
Invasive species
A plant or animal species that is not native to a particular eosystem or location and has a tendency to spread causing damage to the environment, human economy and/or human health
Macroplastic debris
Plastic particles larger than 1mm that are a marine pollutant.
Microplastic debris
Plastic particles smaller than 1mm that are a marine pollutant.
Pollutant
Pollutant is a contaminant that causes adverse change to an ecosystem or environment.
Biodiversity
The number and variety of organisms found within a specified geographic region or ecosystem.
Biogeographic factor
A factor that effects distribution of species and ecosystems in geographic space and time (e.g. island size, climate).
Biotic index
a scale for showing the quality of an environment by indicating the types of organisms present in it.
Captive breeding
The process of breeding animals in controlled environments within well-defined settings, such as wildlife reserves and zoos.
Edge effect
The changes in population or community structures that occur at the boundary of two habitats.
Endangered species
A species which has been categorized by the International Union for Conservation of Nature (IUCN) as likely to become extinct.
Evenness
A measure of biodiversity based on how even the abundance of each species in a geographic region or ecosystem.
Ex situ conservation
Off-site conservation or the conservation of genetic resources outside natural ecosystems.
In situ conservation
On-site conservation or the conservation of genetic resources in natural ecosystems.
Indicator species
A species presence whose absence can be used as a indicator of environmental conditions.
Nature reserve
A protected area of importance for wildlife, flora, fauna which is reserved and managed for conservation.
Richness
A measure of biodiversity based on the number of different species present in a geographic region or ecosystem.
Simpson's reciprocal index
A index that can be used to measure the biodiversity of an ecosystem.
Wildlife corridor
An area of habitat connecting wildlife populations separated by human activities or structures.
Age structure
The distribution of a population's individuals among various age groups.
Bottom-up limting factors
Factors that limit population growth by affecting resources or lower tropic levels (e.g. interspecific competition for resources).
capture-mark-release-recapture
A method used to estimate the population size of mobile animals.
Carrying capacity
The maximum population of a species that a particular ecosystem can sustain (due to limited resources).
Density dependent limiting factors
A factor limiting population growth that increases as the population increases.
Density independent limting factors
A factor limiting population growth that equally effects small and large populations.
Emigration
Decreases to population size by movement of individuals to external populations.
Exponential phase
Phase of unlimited growth of a population in an unlimited environment. Represented by a J-shaped curve when population size is plotted over time.
Immigration
Increases to population size by movement of individuals from external populations.
Mortality
Decreases to population size as a result of death (e.g. predation, senescence)
Natality
Increases to population size through reproduction (i.e. births)
Plateau phase
The population has reached the carrying capacity and population growth ceases due to limited resources. Mortality and death equal natality and Immigration.
Random number generator
A tool used to ensure unbiased sampling points are chosen.
Reproductive status
Whether an organism is capable of participating in the process of reproduction.
Sigmoidal growth curve
A growth curve having a sigmoid or "S" shape (sigmoid curve).
Top-down limiting factors
Population growth pressures applied by other organisms at higher trophic levels, e.g. predation.
Transitional phase
Phase of population growth where the population continues to grow, but increasingly slowly as competition increases as availability of resources are reduced.
Algal bloom
A dense spread of algae on the surface of water caused by a rapid population growth.
Biochemical oxygen demand (BOD)
The amount of oxygen required by aerobic microorganisms to decompose the organic matter in a sample of water. It is used as a measure of the degree of water pollution. Also referred to as biological oxygen demand.
Denitrification
A process facilitated by bacteria, in which nitrates (NO3) break down to molecular nitrogen (N2).
Denitrifying bacteria
Bacteria that facilitate the process known as denitrification, as part of the nitrogen cycle, e.g. Pseudomonas.
Eutrophication
The response of aquatic ecosystems to the addition of artificial or natural nutrients through detergents, fertilizers, or sewage. Commonly an intial algal blooms is followed by a decline in dissolved oxygen.
Insectivorous plants
Plants that derive some or most of their nutrients (but not energy) from trapping and consuming commonly insects (other arthropods, protozoans and animals may also be trapped).
Leaching
The loss of water-soluble nutrients from the soil, due to rain and irrigation. Nutrients lost from soils enter aquatic ecosystems.
Legumes
A plant of the pea family. Most species have symbiotic nitrogen-fixing bacteria in structures called root nodules.
Nitrification
The process by which ammonia is converted to nitrite (NO2-) and then nitrate (NO3-) by microorganisms.
Nitrifying bacteria
Bacteria that facilitate part of the process known as nitrification, as part of the nitrogen cycle, e.g. Nitrosomonas convert ammonia to nitrite and Nitrobacter convert nitrite to nitrate.
Nitrogen fixation
The conversion of atmospheric nitrogen into compounds that plants and other organisms can assimilate, e.g. ammonia.
Nitrogen-fixing bacteria
Microorganisms capable of fixing atmospheric nitrogen into compounds that plants and other organisms can assimilate. Bacteria can be free-living in the soil (e.g. Azotobacter) or living mutualistically with plants roots (e.g. Rhizobium).
Putrefaction
Decomposition of organic matter by microorganisms.
linked genes
Genes located on the same chromosome that tend to be inherited together in genetic crosses
gene loci
specific locations of genes along the chromosome
discrete variation
Inherited characteristic that have a limited number of variations, such as the ability or inability to roll one's tongue
continuous variation
An assemblage of measurements of a phenotypical characteristic which forms from a continuous spectrum of values, such as body height, skin color or hair curl
polygenic inheritance
An additive effect of two or more gene loci on a single phenotypic character
chi-square test
A statistical method used to calculate whether the observed and expected genotype frequencies of a population are significantly different.
dihybrid cross
A cross between two individuals, concentrating on two definable traits, for example pea color and height of pea plant
recombinants
Offspring whose phenotype differs from that of the parents; also called recombinant types
diploid
An organism or cell having two sets of chromosomes or twice the haploid number
gametes
A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
fusion of gametes
occurs when two haploids (an egg and sperm) join to form one zygote (first cell of life)
non-disjunction
meiosis in which there is a failure of paired homologous chromosomes to separate
random orientation
the random position of each pair of chromosomes in the nucleus when the spindle microtubules become attached. Their random orientation will eventually result in which chromosomes end up where.
haploid
An organism or cell having only one complete set of chromosomes
bivalents
A structure in which 2 pairs of homologous sister chromatids have synapsed with one another
crossing over
Process in which homologous chromosomes exchange portions of their chromatids during meiosis.
fertilization
Male sex cell (sperm) unites with female sex cell into one cell (46 chromosomes -- 23 from each).
non-sister chromatids
Chromatids from opposite members of a homologous pair. These cross over at prophase I.
chiasmata
The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.
allele exchange
During crossing over, the switch of alleles for the same genes.
independent assortment
the random distribution of the pairs of genes on different chromosomes to the gametes
synaptomenal complex
where cross over occurs between two non-sister chromatid to allow for cross-over
Gene pool
The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species.
allelic frequency
The percentage of all alleles at a given locus in a population gene pool represented by a particular allele.
reproductive isolation
Separation of species or populations so that they cannot interbreed and produce fertile offspring
speciation
An evolutionary process in which one species splits into two or more species.
polyploidy
A chromosomal alteration in which the organism possesses more than two complete chromosome sets. Found in plants
directional selection
Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.
stabilizing selection
Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes.
disruptive selection
form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle
Allium
The genus of monocotyledonous flowering plants that includes the onion, garlic, chives, scallion, shallot, and the leek as well as hundreds of wild species.
punctuated equilibrium
Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
gradualism
A proposed explanation in evolutionary biology stating that new species arise from the result of slight modifications (mutations and resulting phenotypic changes) over many generations.
hybrid vigour
The increased vigour (eg: growth, litter size, milk production) of crossbred animals