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195 terms

HIMEL(biology)MIDTERM-!!

VOCABULARY ONLY!! (it's a lot)
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matter
anything that occupies space and has mass
element
pure substance that cannot be broken down into other substances by chemical or physical means
trace element
element critical to health that makes up less than 0.01 percent of body mass
compound
substance containing two or more elements chemically combined in a fixed ratio
atom
smallest particle of an element
proton
subatomic particle with a single unit of positive electric charge
electron
subatomic particle with a single unit of negative electric charge
neutron
subatomic particle that has no charge
nucleus
in an atom, the central core that contains protons and neutrons (Concept 4.2); in a cell, the part that houses the cell's genetic material in the form of DNA
atomic number
number of protons in an atom's nucleus; is unique for each element
isotope
one of several forms of an element, each containing the same number of protons in their atoms but a different number of neutrons
radioactive isotope
isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy
ionic bond
chemical bond that occurs when an atom transfers an electron to another atom
ion
atom that has become electrically charged as a result of gaining or losing an electron
covalent bond
chemical bond that forms when two atoms share electrons
molecule
two or more atoms held together by covalent bonds
chemical reaction
breaking of old and formation of new chemical bonds that result in new substances
reactant
starting material for a chemical reaction
product
material created as a result of a chemical reaction
polar molecule
molecule in which opposite ends have opposite electric charges
hydrogen bond
bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule
cohesion
tendency of molecules of the same kind to stick to one another
adhesion
attraction between unlike molecules
thermal energy
total amount of energy associated with the random movement of atoms and molecules in a sample of matter
temperature
measure of the average energy of random motion of particles in a substance
solution
uniform mixture of two or more substances
solvent
substance in a solution that dissolves the other substance and is present in the greater amount
solute
substance in a solution that is dissolved and is present in a lesser amount
aqueous solution
solution in which water is the solvent
acid
compound that donates H+ ions to an aqueous solution and measures less than 7 on the pH scale
base
compound that removes H+ ions from an aqueous solution and that measures more than 7 on the pH scale
pH scale
a range of numbers used to describe how acidic or basic a solution is; ranges from 0 (most acidic) to 14 (most basic)
buffer
substance that maintains a fairly constant pH in a solution by accepting H+ ions when their levels rise and donating H+ ions when their levels fall
organic molecule
carbon-based molecule
inorganic molecule
non-carbon-based molecule
hydrocarbon
organic molecule composed of only carbon and hydrogen atoms
functional group
group of atoms within a molecule that interacts in predictable ways with other molecules
hydrophilic
attracts water molecules
monomer
small molecular unit that is the building block of a larger molecule
polymer
long chain of small molecular units (monomers )
carbohydrate
organic compound made of sugar molecules
monosaccharide
sugar containing one sugar unit
disaccharide
sugar containing two monosaccharaides
polysaccharide
long polymer chain made up of simple sugar monomers
starch
polysaccharide in plant cells that consists entirely of glucose monomers
glycogen
polysaccharide in animal cells that consists of many glucose monomers
cellulose
polysaccharide consisting of glucose monomers that reinforces plant-cell walls
lipid
one of a class of water-avoiding compounds
hydrophobic
avoids water molecules
fat
organic compound consisting of a three-carbon backbone (glycerol) attached to three fatty acids
saturated fat
fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms
unsaturated fat
fat with less than the maximum number of hydrogens in one or more of its fatty acid chains
steroid
lipid molecule with four fused carbon rings
cholesterol
steroid molecule present in the plasma membranes of animal cells
protein
polymer constructed from a set of 20 amino acid monomers
amino acid
monomer that makes up proteins; contains carboxyl and amino functional groups
polypeptide
chain of linked amino acids
denaturation
loss of normal shape of a protein due to heat or other factor
activation energy
minimum amount of energy required to trigger a chemical reaction
catalyst
agent that speeds up chemical reactions
enzyme
specialized protein that catalyzes the chemical reactions of a cell
substrate
specific reactant acted on by an enzyme
active site
region of an enzyme into which a particular substrate fits
cell theory
generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living things
micrograph
photograph of the view through a microscope
organelle
part of a cell with a specific function
plasma membrane
thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings
nucleus
in an atom, the central core that contains protons and neutrons (Concept 4.2); in a cell, the part that houses the cell's genetic material in the form of DNA
cytoplasm
region of a cell between the nucleus and the plasma membrane
cell wall
strong wall outside a plant cell's plasma membrane that protects the cell and maintains its shape
prokaryotic cell
cell lacking a nucleus and most other organelles
eukaryotic cell
cell with a nucleus (surrounded by its own membrane) and other internal organelles
phospholipid bilayer
two-layer "sandwich" of molecules that surrounds a cell
diffusion
net movement of the particles of a substance from where they are more concentrated to where they are less concentrated
equilibrium
point at which the number of diffusing molecules moving in one direction is equal to the number moving in the opposite direction
selectively permeable membrane
membrane that allows some substances to pass more easily than others and blocks the passage of some substances altogether
passive transport:
diffusion across a membrane requiring only the random motion of molecules with no energy expended by the cell
facilitated diffusion
pathway provided by transport proteins that helps certain molecules pass through a membrane
osmosis
passive transport of water across a selectively permeable membrane
hypertonic
having a higher concentration of solute than another solution
hypotonic
having a lower concentration of solute than another solution
isotonic
having a solute concentration equal to that of another solution
active transport
movement of molecules across a membrane requiring energy to be expended by the cell
vesicle
small membrane-bound sac that functions in moving products into, out of, and within a cell
exocytosis
process of exporting proteins from a cell by a vesicle fusing with the plasma membrane and spilling the proteins outside the cell
endocytosis
process of taking material into a cell within vesicles that bud inward from the plasma membrane
nuclear envelope
double membrane that surrounds a cell nucleus
nucleolus
ball-like mass of fibers and granules in a cell nucleus
ribosome
cluster of proteins and nucleic acids that constructs proteins in a cell
endoplasmic reticulum
network of membranes within a cell's cytoplasm that produces a variety of molecules
Golgi apparatus
cellular organelle that modifies, stores, and routes cell products
vacuole
membrane-bound sac that buds from the endoplasmic reticulum or the Golgi apparatus
lysosome
`membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides
chloroplast
organelle found in some plant cells and certain unicellular organisms where photosynthesis takes place
mitochondria
cellular organelles where cellular respiration occurs
ATP
(adenosine triphosphate) main energy source that cells use for most of their work
microtubule
straight, hollow tube of proteins that gives rigidity, shape, and organization to a cell
microfilament
solid rod of protein, thinner than a microtubule, that enables a cell to move or change shape
flagella
long, thin, whip-like structures, with a core of microtubules, that enable some cells to move
cilia
short structures projecting from a cell and containing bundles of microtubules that move a cell through its surroundings or move fluid over the cell's surface
chromatin
combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell
chromosome
condensed threads of genetic material formed from chromatin as a cell prepares to divide
sister chromatid
one of a pair of identical chromosomes created before a cell divides
centromere
region where two sister chromatids are joined tightly together
cell cycle
sequence of events from the production of a eukaryotic cell to the time the cell itself reproduces
interphase
stage of the cell cycle during which a cell carries out its metabolic processes and performs its functions in the body
mitotic phase
stage of the cell cycle when a cell is actively dividing
mitosis
process by which the nucleus and duplicated chromosomes of a cell divide and are evenly distributed, forming two daughter nuclei
cytokinesis
process by which the cytoplasm of a cell is divided in two; usually follows mitosis and meiosis
spindle
framework of microtubules that guide the movement of chromosomes during mitosis and meiosis
centrosome
region of cytoplasmic material that in animal cells contains structures called centrioles
prophase
first stage of mitosis and of meiosis I and II, when the already replicated chromosomes condense
metaphase
second stage of mitosis and of meiosis I and II when the spindle is fully formed and all of the chromosomes are held in place
anaphase
third phase of mitosis and of meiosis I and II, in which the sister chromatids separate and move toward the poles of the spindle
telophase
final stage of mitosis and of meiosis I and II, in which the chromosomes reach the spindle poles, nuclear envelopes form around each set of daughter chromosomes, and the nucleoli reappear
meiosis
type of cell division that produces cells with half as many chromosomes as the parent cell
karyotype
display of a person's 46 chromosomes
homologous chromosome
one of a matching pair of chromosomes, one inherited from each parent
diploid
having two homologous sets of chromosomes
haploid
having a single set of chromosomes
trait
variation of a particular inherited character
genetics
study of heredity
cross-fertilization
process by which sperm from one flower's pollen fertilizes the eggs in a flower of a different plant
hybrid
offspring of two different true-breeding varieties
monohybrid cross
mating of two organisms that differ in only one character
allele
alternative form of a gene
homozygous
having identical alleles for a gene
heterozygous
having different alleles for a gene
dominant
descriptive of an allele in a heterozygous individual that appears to be the only one affecting a trait
recessive
descriptive of an allele in a heterozygous individual that does not appear to affect a trait
Punnett square
diagram showing the probabilities of the possible outcomes of a genetic cross
phenotype
observable traits of an organism
genotype
genetic makeup of an organism; an organism's combination of alleles
testcross
mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual
dihybrid cross
mating of two organisms that differ in two characters
intermediate inheritance
inheritance in which heterozygotes have a phenotype intermediate between the phenotypes of the two homozygotes
codominance
inheritance pattern in which a heterozygote expresses the distinct traits of both alleles
polygenic inheritance
combined effect of two or more genes on a single character
chromosome theory of inheritance
generalization that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns
gene locus
specific location of a gene on a chromosome
genetic linkage
tendency for alleles of genes on the same chromosome to be inherited together
sex-linked gene
gene located on a sex chromosome
virus
package of nucleic acid wrapped in a protein coat that must use a host cell's machinery to reproduce itself
bacteriophage
: virus that infects bacteria; also called a "phage"
deoxyribonucleic acid (DNA
molecule responsible for inheritance; nucleic acid that contains the sugar deoxyribose
nucleotide
building block (monomer) of nucleic acid polymers
nitrogenous base
single or double ring of carbon and nitrogen atoms with attached functional groups, found in nucleic acids
pyrimidine
single-ring nitrogenous base
purine
double-ring nitrogenous base
double helix
two strands of nucleotides wound about each other; structure of DNA
DNA replication
process of copying DNA molecules
DNA polymerase
enzyme that makes the covalent bonds between the nucleotides of new DNA strands
ribonucleic acid (RNA
nucleic acid containing the sugar ribose
transcription
process by which a DNA template is used to produce a single-stranded RNA molecule
translation
process by which a sequence of nucleic acids in RNA is used to direct the production of a chain of specific amino acids
codon
in RNA, a three-base "word" that codes for one amino acid
messenger RNA (mRNA
RNA molecule transcribed from a DNA template
RNA polymerase
transcription enzyme that links RNA nucleotides together
intron
internal noncoding region in RNA transcript
exon
coding region in RNA transcript
RNA splicing
process by which the introns are removed from RNA transcripts and the remaining exons are joined together
transfer RNA (tRNA
RNA that translates the three-letter codons of mRNA to amino acids
anticodon
in tRNA, a triplet of nitrogenous bases that is complementary to a specific codon in mRNA
ribosomal RNA (rRNA
RNA component of ribosomes
evolution
generation-to-generation change in the proportion of different inherited genes in a population that account for all of the changes that have transformed life over an immense time
adaptation
inherited characteristic that improves an organism's ability to survive and reproduce in a particular environment
descent with modification
process by which descendants of ancestral organisms spread into various habitats and accumulate adaptations to diverse ways of life
natural selection
process by which individuals with inherited characteristics well-suited to the environment leave more offspring than do other individuals
fossil
preserved remains or marking left by an organism that lived in the past
fossil record
chronological collection of life's remains in sedimentary rock layers
extinct
no longer existing as a living species on Earth
homologous structure
similar structure found in more than one species that share a common ancestor
vestigial structure
remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species
population
group of individuals of the same species living in a particular area at the same time
variation: difference among members of a species
artificial selection
selective breeding of domesticated plants and animals to produce offspring with desired genetic traits
gene pool
all of the alleles in all the individuals that make up a population
microevolution
evolution on the smallest scale—a generation-to-generation change in the frequencies of alleles within a population
Hardy-Weinberg equilibrium
condition that occurs when the frequency of alleles in a particular gene pool remain constant over time
condition that occurs when the frequency of alleles in a particular gene pool remain constant over time
change in the gene pool of a population due to chance
gene flow
exchange of genes between populations
fitness
contribution that an individual makes to the gene pool of the next generation compared to the contributions of other individuals
antibiotic
medicine that kills or slows the growth of bacteria
biological species concept
definition of a species as a population or group of populations whose members can breed with one another in nature and produce fertile offspring
macroevolution
major biological changes evident in the fossil record
speciation
formation of new species
formation of new species
condition in which a reproductive barrier keeps two species from interbreeding
geographic isolation
separation of populations as a result of geographic change or migration to geographically isolated places
adaptive radiation
evolution from a common ancestor of many species adapted to diverse environments
punctuated equilibrium
evolutionary model suggesting species often diverge in spurts of relatively rapid change, followed by long periods of little change
embryology
study of multicellular organisms as they develop from fertilized eggs to fully formed organisms
geologic time scale
Earth's history organized into four eras: Precambrian, Paleozoic, Mesozoic, and Cenozoic
radiometric dating
determination of absolute ages of rocks and fossils through calculations based on a radioactive isotope's fixed rate of decay
half-life
time it takes for 50 percent of a radioactive isotope sample to decay
continental drift
motion of continents about Earth's surface on plates of crust floating on the hot mantle
mass extinction
episode of great species loss