AP Biology Vocabulary & Roots: Ch. 8
1. activation energy- The amount of energy that reactants must absorb before a chemical reaction
will start; also called free energy of activation.
2. active site-The specific portion of an enzyme that binds the substrate by means of multiple weak
interactions and that forms the pocket in which catalysis occurs.
3. ATP (adenosine triphosphate)-An adenine-containing nucleoside triphosphate that releases free
energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions
in cells.
4. allosteric regulation-The binding of a regulatory molecule to a protein at one site that affects the
function of the protein at a different site.
5. anabolic pathway-A metabolic pathway that consumes energy to synthesize a complex molecule
from simpler compounds.
6. bioenergetics-(1) The overall flow and transformation of energy in an organism. (2) The study of
how energy flows through organisms.
7. catabolic pathway-A metabolic pathway that releases energy by breaking down complex
molecules to simpler compounds.
8. catalyst-A chemical agent that increases the rate of a reaction without being consumed by the
reaction.
9. chemical energy-Energy available in molecules for release in a chemical reaction; a form of
potential energy.
10. coenzyme- An organic molecule serving as a cofactor. Most vitamins function as coenzymes in
metabolic reactions.
11. cofactor-Any nonprotein molecule or ion that is required for the proper functioning of an
enzyme. Cofactors can be permanently bound to the active site or may bind loosely with the
substrate during catalysis.
12. competitive inhibitor-A substance that reduces the activity of an enzyme by entering the active
site in place of the substrate whose structure it mimics.
13. cooperativity-A kind of allosteric regulation whereby a shape change in one subunit of a
protein caused by substrate binding is transmitted to all the others, facilitating binding of subsequent
substrate molecules.
14. endergonic reaction-A nonspontaneous chemical reaction, in which free energy is absorbed
from the surroundings.
15. energy-The capacity to cause change, especially to do work (to move matter against an
opposing force).
16. energy coupling-In cellular metabolism, the use of energy released from an exergonic reaction
to drive an endergonic reaction.
17. entropy-A measure of disorder, or randomness.
18. enzyme-A macromolecule serving as a catalyst, a chemical agent that changes the rate of a
reaction without being consumed by the reaction.
19. enzyme-substrate complex-A temporary complex formed when an enzyme binds to its
substrate molecule(s).
20. exergonic reaction-A spontaneous chemical reaction, in which there is a net release of free
energy.
21. feedback inhibition-A method of metabolic control in which the end product of a metabolic
pathway acts as an inhibitor of an enzyme within that pathway.
22. first law of thermodynamics-The principle of conservation of energy: Energy can be
transferred and transformed, but it cannot be created or destroyed.
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23. free energy-The portion of a biological system’s energy that can perform work when
temperature and pressure are uniform throughout the system. (The change in free energy of a
system is calculated by the equation ΔG = ΔH – TΔS, where H is enthalpy [in biological systems,
equivalent to total energy], T is absolute temperature, and S is entropy.)
24. heat-The total amount of kinetic energy due to the random motion of atoms or molecules in a
body of matter; also called thermal energy. Heat is energy in its most random form.
25. hemoglobin-An iron-containing protein in red blood cells that reversibly binds oxygen.
26. induced fit- Induced by entry of the substrate, the change in shape of the active site of an
enzyme so that it binds more snugly to the substrate.
27. kinetic energy-The energy associated with the relative motion of objects. Moving matter can
perform work by imparting motion to other matter.
28. metabolic pathway-A series of chemical reactions that either builds a complex molecule
(anabolic pathway) or breaks down a complex molecule into simpler compounds (catabolic
pathway).
29. metabolism-The totality of an organism’s chemical reactions, consisting of catabolic and
anabolic pathways, which manage the material and energy resources of the organism.
30. noncompetitive inhibitor-A substance that reduces the activity of an enzyme by binding to a
location remote from the active site, changing the enzyme’s shape so that the active site no longer
functions effectively.
31. order-In classification, the taxonomic category above the level of family.
32. phosphorylated-Referring to a molecule that is covalently bonded to a phosphate group.
33. potential energy-The energy that matter possesses as a result of its location or spatial
arrangement (structure).
34. ribose-The sugar component of RNA nucleotides.
35. second law of thermodynamics- The principle stating that every energy transfer or
transformation increases the entropy of the universe. Ordered forms of energy are at least partly
converted to heat.
36. substrate-The reactant on which an enzyme works.
37. Thermal energy-See heat.
38. thermodynamics-The study of energy transformations that occur in a collection of matter. See
first law of thermodynamics; second law of thermodynamics.
Word Roots
allo- = different (allosteric site: a specific receptor site on some part of an enzyme molecule remote
from the active site)
ana- = up (anabolic pathway: a metabolic pathway that consumes energy to build complex
molecules from simpler ones)
bio-= life (bioenergetics: the study of how organisms manage their energy resources)
cata- = down (catabolic pathway: a metabolic pathway that releases energy by breaking down
complex molecules into simpler ones)
endo- = within (endergonic reaction: a reaction that absorbs free energy from its surroundings)
ex- = out (exergonic reaction: a reaction that proceeds with a net release of free energy)
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kinet- = movement (kinetic energy: the energy of motion)
therm- = heat (thermodynamics: the study of the energy transformations that occur in a collection
of matter)
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