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Chapter 1, 2, 3

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prokaryotes
unicellular organisms that do not have nuclei
photosynthesis
metabolic processes carried out by green plants and cyanobacteria, by which visible light is trapped and the energy used to convert CO2 into organic compounds
organelles
any of the membrane-enclosed structures within a eukaryotic cell
eukaryotes
organisms whose cells contain their genetic material inside a nucleus
endosymbiosis
the theory that the eukaryotic cell evolved via the engulfing of one prokaryotic cellby another
cellular specialization
in multicellular organisms, the division of labor such that different cell types become responsible for different functions
mutations
a change in the genetic material not caused by recombination
binomial
a taxomic naming system in which species are given two names
domains
the three monophyletic branches of life
model systems
small group of species that are the subject of extensive research; organism that adapt well to laboratory situations and findings from experiments on them can apply across a broad range of species
genome
the complete DNA sequence for a particular organism or individual
nucleotides
the basic chemical unit in nucleic acids, consisting of a pentose sugar, a phosphate group, and a nitrogen-containing base
DNA
the fundamental hereditary material of all living organisms
proteins
long chain polymer of amino acids with twenty different common side chains
homeostasis
the maintenance of steady state, such as a constant temperature, by means of physiological or behavioral feedback responses
natural selection
the differential contribution of offspring to the next generation by different types belonging to the same population
adaptations
a particular structure, physiological process, or behavior that makes an organism better able to survive and reproduce
evolution
any gradual change
theory
a far-reaching explanation of observed facts that is supported by such a wide body of evidence, with no significant contradictory evidence, that is scientifically accepted as a factual framework
natural history
the characteristics of a group of organisms, such as how the organisms get their food, reproduce, behave, regulate their internal environments, and interact with other organisms
quantify
to assign numerical values to observations through measurement
hypothesis
a tentative answer to a question from which testable predictions can be generated
deductive logic
to make predictions based on the hypothesis
controlled experiment
an experiment in which a sample is divided into groups whereby experimental groups are exposed to manipulations of an independent variable while one group serves as an untreated control. the data from various groups are then compared to see if there are changes in a dependent variable as a result of the experimental manipulation
variable
in a controlled experiment, a factor that is manipulated to test its effect on a phenomenon
comparative experiment
experimental design in which data from various unmanipulated samples or population are compared, but in which variables are not controlled or even necessarily indentified
null hypothesis
in statistics, the premise that any differences observed in an experiment are simply the result of random differences that arise from drawing two finite samples from the same population
data
quantified observations about a system under study
atoms
the smallest unit of chemical element
nucleus
the centrally located compartment of eukaryotic cells that is bounded by a double membrane and contains the chromosomes
electrons
a subatomic particle outside the nucleus carrying a negative charge and very little mass
protons
a subatomic particle with a single positive charge. the number of these determine its element
neutrons
one of the three fundamental particles of matter, with mass slightly larger than that of a proton and no electrical charge
element
a substance that cannot be converted to simpler substances by ordinary chemical means
atomic number
the number of protons in the nucleus of an atom
Bohr model
a model for atomic structure that depicts the atom as largely empty space, with a central nucleus surrounded by electrons in orbits, or electron shells, at various distances from the nucleus
electron shells
the region surrounding the atomic nucleus at a fixed energy level in which electrons orbit
molecules
a chemical substance made up of two or more atoms joined by covalent bonds or ionic attractions
chemical bond
an attractive force stably linking two atoms
ion
an electrically charged particle that forms when an atom gains or loses an electron
cations
an ion with one or more positive charges
anions
a negatively charged ion
ionic bonds
an electrostatic attraction between positively and negatively charged ions
covalent bond
chemical bond based on the sharing of electrons between two atoms
electronegativity
the tendency of an atom to attract electrons when it occurs as part of a compound
polar covalent pond
a covalent bond in which the electrons are drawn to one nucleus more than the other, resulting in an unequal distributions of charge
hydrogen bond
a weak electrostatic bond which arises from the attraction between the slight positice charge on a hydrogen atom and a slight negative charge on a nearby oxygen or nitrogen atom
heat of vaporization
the energy that must be supplied to convert a molecule from a liquid to a gas at its boiling point
cohesion
the tendency of molecules to stick together
hydrophilic
having an affinity for water
hydrophobic
having no affinity for water
functional groups
a characteristic combination of atoms that contribute specific properties when attached to larger molecules
polymers
a larger molecule made up of similar or identical subunits called monomers
monomers
a small molecule, two or more of which can be combined to form oligomers or polymers
condensation
a chemical reaction in which two molecules become connected by a covalent bond and a molecules of water is released
hydrolysis
a chemical reaction that breaks a bond by inserting the components of water
carbohydrates
organic compounds containing carbon, hydrogen, and oxygen in the ratio 1:2:1
monosaccharides
a simple sugar; makes up oligosaccharides and polysaccharides
glycosidic linkages
bond between carbohydrate molecules through an intervening oxygen atom
disaccharide
a carbohydrate made up of two monosaccharides
oligosaccharides
a polymer containing a small number of monosaccharides
polysaccharides
a macromolecule composed of many monosaccharides; ex. cellulose and starch
lipids
nonpolar, hydrophobic molecules that include fats, oils, waxes, steroids, and the phospholipids that make up biological membranes
triglycerides
a simple lipid in which three fatty acids are combined with one molecule of glycerol
glycerol
a three-carbon alcohol with three hydroxyl groups; a component of phospholipids and triglycerides
fatty acid
a molecule made up of a long nonpolar hydrocarbon chain and a polar carboxyl group
saturated fatty acid
a fatty acid in which all the bonds between carbon atoms in the hydrocarbon chain are single bonds - that is all the bonds are saturated with hydrogen atoms
unsaturated fatty acid
a fatty acid whose hydrocarbon chain contains one or more double bonds
amphipatic
having both hydrophilic and hydrophobic regions
phospholipids
a lipid containing a phosphate group; an important constituent of cellular membranes
bilayer
a structure that is two layers in thickness; most often referred to the phospholipid ______ of membranes
phospholipid bilayer
the basic structural unit of biological membranes; a sheet of phospholipids two molecules thick in which the phospholipids are lined up with their hydrophobic "tails" packed together
chemical reaction
the change in the composition or distribution of atoms of a substance with consequent alterations in properties
reactants
a chemical substance that enters into a chemical reaction with another substance
products
the molecules that result from the completion of a chemical reaction
metabolism
the sum total of the chemical reactions that occur in an organism, or some subset of that total
potential energy
the energy of a state or position that is stored energy
kinetic energy
the energy of movement, the type of energy that does work
anabolic reactions
a synthetic reaction in which simple molecules are linked to form more complex ones; requires an input of energy and captures it in the chemical bonds that are formed
catabolic reactions
a synthetic reaction in which complex molecules are broken down into simpler ones and energy is released
laws of thermodynamics
laws derived from studies of the physical properties of energy and the ways energy interacts with matter
nucleic acids
a polymer made up of nucleotides, specialized for the storage, transmission, and expression of genetic information
DNA
the fundamental hereditary material of all living organisms.
RNA
an often single-stranded nucleic acid whose nucleotides use ribose rather than deoxyribose and in which the base uracil replaces thymine found in DNA
nucleotide
the basic chemical unit in nucleic acids, consisting of a pentose sugar, a phosphate group, and a nitrogen containing base
base
a substance that can accept a hydrogen ion in solution; in nucleic acids, the purine or pyrimidine that is attached to each sugar in the sugar-phosphate backbone
pyrimidine
one of the two types of nitrogenous bases in nucleic acids; it pairs with a specific purine
purine
one of the two types of nitrogenous bases in nucleic acids; each pairs with a specific pyrimidine
deoxyribose
a five carbon sugar found in nucleotides and DNA
ribose
a five carbon sugar in nucleotides and RNA
phosphodiester linkage
the connection in nucleic acid strand, formed by linking two nucleotides
complimentary base pairing
The AT or AU, TA or UA, CG, and GC pairing of bases in double-stranded DNA, in transcription, and between tRNA and mRNA
transcription
when DNA sequences are copied into RNA
translation
when the nucleotide sequence is used to specify a sequence of amino acids in a polypeptide chain
gene expression
the overall process of transcription and translation
genome
the complete DNA sequence for a particular organism or individual
gene
a unit of heredity
enzymes
catalytic proteins that speed up biochemical reactions
defensive proteins
recognize and respond to substances or particles that invade the organism from the environment
hormonal and regulatory proteins
control physiological processes
receptor proteins
receive and respond to molecular signals from inside and outside the organism
storage proteins
store chemical building blocks for later use
structural proteins
provide physical stability and movement
transport proteins
carry substances within the organism
genetic regulatory proteins
regulate when, how, and to what extent a gene is expressed
amino acids
an organic compound containing both NH2 and COOH groups; proteins are its polymers
R group
the distinguishing group of atoms of a particular amino acid
disulfide bridge
the covalent bond between two sulfur atoms linking two molecules or remote parts of the same molecule
peptide linkage
the bond between amino acids in a protein; formed between a carboxyl group and amino group with the loss of water molecules
primary structure
the specific sequence of amino acids in a protein
secondary structure
localized regularities of structure, such as the alpha helix and the beta pleated sheet
alpha helix
a prevalent type of secondary protein structure; a right-handed spiral
beta pleated sheet
a type of protein secondary structure; results from hydrogen bonding between polypeptide regions running antiparallel to each other
tertiary structure
the relative locations in three-dimensional space of all the atoms in the molecule; the overall shape of the protein
denaturation
loss of activity of an enzyme or nucleic acid molecule as a result of structural changes induced by heat or other means
quarternary structure
the specific three-dimensional arrangement of protein subunits
catalysts
a chemical substance that accelerates a reaction without itself being consumed in the overall course of the reaction; they lower the activation energy or a reaction
transition state
in an enzyme-catalyzed reaction, the reactive condition of the substrate after there has been sufficient input of energy to initiate the reaction
activation energy
the energy barrier that blocks the tendency for a chemical reaction to occur
substrates
the molecule or molecules on which and enzyme exerts catalytic action
active site
the region on the surface of an enzyme or ribozyme where the substrate binds, and where catalysis occurs
enzyme-substrate complex
an intermediate in an enzyme-catalyzed reaction; consists of the enzyme bound to its substrate
coenzyme
a carbon-containing molecule that is required for the action of one or more enzymes
prosthetic groups
distinctive, non-amino acid atoms or molecular groupings that are permanently bound to their enzymes
competitive inhibitor
a nonsubstrate that binds to the active sire of an enzyme and thereby inhibits binding of its substrate
noncompetitive inhibitor
a nonsubstrate that inhibits the activity of an anzyme by binding to a site other than its active site
allosteric regulation
regulation of the activity of a protein by the binding of an effector molecule to a site other than the active site
feedback inhibition
a mechanism for regulating a metabolic pathway in which the end product of the pathway can bind to an inhibit the enzyme that catalyzes the first committed step in the pathway
isoenzymes
catalyze the same reaction but have different chemical compositions and physical properties