AP Biology Chapter 8 Study Guide: Metabolism and Enzymes

Vocabulary flashcards covering metabolism, thermodynamics, ATP hydrolysis, enzyme activity, and metabolic regulation from AP Biology Chapter 8.

Metabolism

The totality of an organism's chemical reactions, consisting of anabolic and catabolic pathways.

Metabolic pathway

A series of chemical reactions that begins with a specific molecule and ends with a product, with each step catalyzed by a specific enzyme.

Anabolism

Metabolic pathways that consume energy to build complex molecules from simpler ones.

Catabolism

Metabolic pathways that release energy by breaking down complex molecules into simpler compounds.

Kinetic energy

The energy associated with the relative motion of objects.

Potential energy

The energy that matter possesses because of its location or structure.

Heat

Thermal energy in transfer from one body or system to another.

Chemical energy

Potential energy available for release in a chemical reaction.

First law of thermodynamics

The principle stating that energy can be transferred and transformed, but it cannot be created or destroyed.

Second law of thermodynamics

The principle stating that every energy transfer or transformation increases the entropy of the universe.

Entropy

A measure of molecular disorder, or randomness, in a system.

Spontaneous

A process that occurs without an overall input of energy, increasing the entropy of the universe.

Free energy

The portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system.

Endergonic

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings (such as in photosynthesis).

Exergonic

A spontaneous chemical reaction that releases free energy into the surroundings (such as cellular respiration and ATP hydrolysis).

Equilibrium

A state of balance in a chemical reaction where forward and reverse reaction rates are equal and free energy is at a minimum.

Energy coupling

The use of an exergonic process, such as ATP hydrolysis, to drive an endergonic process like active transport.

ATP

Adenosine triphosphate; an adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed, driving cellular work.

Phosphorylation

The transfer of a phosphate group from ATP to another molecule, creating a phosphorylated intermediate with higher free energy.

The ATP cycle

The continuous cycle by which ATP is hydrolyzed to ADP and inorganic phosphate to release energy, and regenerated from ADP and inorganic phosphate using energy from catabolism.

Enzyme

A macromolecule that acts as a biological catalyst, lowering the activation energy of a chemical reaction without being consumed by it.

Catalysis

A process by which a catalyst selectively increases the rate of a chemical reaction without being consumed by the reaction.

Activation energy

The initial investment of energy required to start a chemical reaction, which enzymes lower to accelerate reaction rates.

Substrate

The specific reactant molecule upon which an enzyme acts.

Enzyme-substrate complex

A temporary complex formed when an enzyme binds to its specific substrate.

Active site

The specific region on an enzyme where the substrate binds and catalysis occurs.

Induced fit

The change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by substrate binding.

Cofactor

Any non-protein molecule or ion that is required for the proper functioning of an enzyme.

Coenzyme

An organic cofactor, such as a vitamin, that aids in enzyme function.

Competitive inhibitor

A substance that reduces enzyme activity by entering the active site in place of the substrate whose structure it mimics.

Noncompetitive inhibitor

A substance that impedes enzyme reactions by binding to a site away from the active site, altering the enzyme's shape and functional effectiveness.

Allosteric regulation

The binding of a regulatory molecule (activator or inhibitor) to a protein at one site that affects the function of the protein at another site.

Cooperativity

A form of allosteric regulation where substrate binding to one active site of a multisubunit enzyme triggers a shape change in all subunits, increasing catalytic activity at other sites.

Feedback inhibition

A method of metabolic control in which the final product of a metabolic pathway acts as an inhibitor of an earlier (often the first) step of the pathway.

Denaturation

The loss of an enzyme's functional 3D shape and biological activity, caused by adverse environmental conditions such as extreme pH or temperature.