AP Biology Unit 3 Vocabulary

Flashcards covering vocabulary terms from AP Biology Unit 3: Cellular Energetics.

Primary Structure (Enzyme)

Made up of polypeptide chains; different amino acids determine protein folding.

Secondary Structure (Enzyme)

Polypeptide chains are folded into alpha-helixes and beta-pleated sheaths.

Tertiary Structure (Enzyme)

3D folding of the enzyme, including the active site.

Quaternary Structure (Enzyme)

Spatial relationship between the subunits.

Active Site

The specific region of an enzyme where the substrate binds and catalysis occurs. Must be complementary to the substrate.

Lock-and-Key Hypothesis

The active site has a very specific shape; only substrates complementary to the active site can bind.

Induced Fit

The active site is malleable and flexible; the enzyme changes shape as the substrate binds.

Inhibitors

Substances that compete with the substrate and reduce the rate of enzyme-catalyzed reactions.

Reversible Competitive Inhibitors

Inhibitors with a similar shape to the substrate, fitting into the active site, reversible by increasing substrate concentration.

Reversible Non-Competitive Inhibitors

Inhibitors with a different shape from the substrate, binding to other parts of the enzyme, preventing enzyme-substrate complex formation.

Enzyme Catalysis

The process by which enzymes speed up reactions inside (intracellular) or outside (extracellular) cells.

Enzyme-Substrate Complex

The complex formed when an enzyme binds to its substrate.

Activation Energy

The energy required for a reaction to occur; enzymes lower this energy.

Optimum Temperature

The most effective temperature for enzymes to work at the maximum rate; exceeding this can cause denaturation.

Denaturation (Enzyme)

Change in the shape of an enzyme, preventing it from fitting with the substrate.

Optimum pH

The specific pH at which an enzyme is most active; extreme pH levels can cause denaturation.

ATP (Adenosine Triphosphate)

The basic form of cellular energy; hydrolyzed to produce energy.

Metabolism

The sum of all chemical processes that occur in an organism, including catabolism (breaking down) and anabolism (synthesis).

Photosynthesis

The process by which living organisms convert light energy into chemical energy, producing sugars from carbon dioxide and water.

Photosystems (PS)

Pigments that absorb light energy in the thylakoid membrane.

Cyclic Photophosphorylation

A process in the light-dependent reactions where electrons cycle through Photosystem I, producing ATP.

Non-cyclic Photophosphorylation

A process in the light-dependent reactions involving both Photosystems I and II, producing ATP, NADPH, and oxygen.

Calvin Cycle (Light-Independent Reaction)

The process in photosynthesis where carbon dioxide is converted into glucose using ATP and NADPH.

Glycolysis

The initial stage of cellular respiration where glucose is broken down into pyruvate in the cytoplasm.

Link Reaction

The step in cellular respiration where pyruvate is converted to Acetyl CoA in the mitochondrial matrix.

Krebs Cycle

A series of reactions in the mitochondrial matrix that oxidizes Acetyl CoA, producing ATP, NADH, and FADH₂.

Electron Transport Chain (ETC)

A series of protein complexes that transfer electrons, creating a proton gradient for ATP synthesis in the inner mitochondrial membrane.

Anaerobic Respiration

Cellular respiration in the absence of oxygen, producing less ATP.

Fermentation

An anaerobic process by which energy can be released from glucose, producing ethanol or lactic acid.

Fitness

The ability of an organism to survive and reproduce.