AP®︎ Biology: Unit 3 Flashcards

A protein catalyst that speeds cellular reactions by lowering activation energy.

The minimum energy required for reactants to reach the transition state and react.

The specific region where substrate binds and catalysis occurs.

The reactant molecule an enzyme binds and acts on.

The temporary association formed when a substrate binds an enzyme's active site.

The property that allows only particular substrates to bind and be catalyzed.

A model where substrate binding causes the enzyme to change shape for tighter binding.

Primary amino acid sequence; secondary local folding; tertiary overall shape; quaternary subunit arrangement.

Control of activity by binding at another site that changes the active site's shape.

Refolding back into an active shape after denaturing conditions are removed, restoring activity in some cases.

Low temperatures slow collisions; rising temperatures increase rate until an optimum, then denaturation reduces activity.

Each enzyme works best at a specific pH; deviations disrupt hydrogen bonds and reduce activity.

Reaction efficiency depends on relative amounts of reactants and products; more substrate usually speeds forward reactions.

Competitive inhibitors block the active site, while noncompetitive inhibitors bind elsewhere and change enzyme shape.

A change or loss of a protein's functional shape, often caused by heat, pH changes, or chemicals, that disrupts the active site and reduces or eliminates activity.

Energy is conserved, and every energy transfer increases entropy in the universe.

Cells must gain more usable energy than they lose to maintain order and function.

Exergonic reactions drive endergonic reactions, often through ATP as an intermediate.

Exergonic reactions release free energy; endergonic reactions require an energy input.

The cell's main energy carrier, storing usable energy in phosphate bonds.

Severe disruption of internal organization or energy transfer causes cells and organisms to die.

A series of reactions where each product becomes the next reactant, enabling controlled energy transfer.

Shared energy-processing pathways across all domains of life provide evidence of common ancestry.

A measure of disorder that increases in the universe during energy transfers.

Process that uses light, CO2, and H2O to produce carbohydrates and O2.

6CO2 + 6H2O + light energy -> C6H12O6 + 6O2.

Organelle where photosynthesis occurs, containing stroma and thylakoid membranes.

Fluid inside the inner chloroplast membrane where the Calvin cycle occurs.

Flattened membrane sacs stacked into grana where the light reactions occur.

Stroma reactions that use ATP and NADPH to fix CO2 into carbohydrates.

Primary photosynthetic pigment that absorbs light and excites electrons.

Electron carrier pair where NADP+ gains electrons and becomes high-energy NADPH.

Higher H+ concentration inside thylakoids than in the stroma after electron transport.

Incorporation of inorganic CO2 into organic molecules during the Calvin cycle.

Earliest form of this process, first evolving in bacteria before eukaryotes.

Photosynthetic prokaryotes whose oxygen production helped create Earth's oxygen-rich atmosphere.

Idea that chloroplasts evolved from engulfed photosynthetic cyanobacteria in early eukaryotes.

Thylakoid reactions that use light energy to produce ATP and NADPH.

Thylakoid complexes that absorb light, excite electrons, and replace PSII electrons using water.

Membrane protein that uses proton flow to make ATP during the light reactions.

Process that breaks down organic molecules to make ATP through enzyme-catalyzed energy transfer.

Aerobic uses oxygen and yields much more ATP; fermentation regenerates NAD+ without oxygen and yields 2 ATP.

Double-membraned organelle where pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation occur in eukaryotes.

Highly folded membrane containing the ETC and ATP synthase; folds increase surface area for ATP production.

Innermost compartment of the mitochondrion where pyruvate oxidation and the Krebs cycle occur.

Compartment between mitochondrial membranes where protons accumulate during electron transport.

Conversion of pyruvate to acetyl CoA in mitochondria, releasing CO2 and producing NADH.

Matrix pathway that oxidizes acetyl CoA, releasing CO2 and producing ATP, NADH, and FADH2.

Electron carrier that accepts high-energy electrons and hydrogen, then delivers them to the ETC.

Electron carrier reduced during the Krebs cycle that transfers electrons to the ETC.

Difference in H+ concentration and charge across a membrane created by electron transport.

Diffusion of protons through ATP synthase down their gradient, driving ATP formation.

Membrane enzyme that uses proton flow to phosphorylate ADP into ATP.

The matrix has lower H+ concentration and higher pH than the intermembrane space.

Direct enzymatic transfer of a phosphate group to ADP to form ATP.

Anaerobic pathway that reduces pyruvate to lactate and regenerates NAD+ for glycolysis.

Anaerobic pathway that converts pyruvate to ethanol and CO2 while regenerating NAD+.

When proton gradient energy is released as heat instead of being used to make ATP.

In prokaryotes, electron transport and proton pumping occur across the plasma membrane.

Final molecule that receives electrons; in aerobic respiration, oxygen forms water.

Two-carbon molecule formed from pyruvate that enters the Krebs cycle.

A conserved cytoplasmic pathway that splits glucose into two pyruvate and captures energy as a net 2 ATP and 2 NADH.

A series of membrane proteins that pass electrons through redox reactions and pump protons across a membrane, building a gradient used to make ATP.

ATP production linked to electron transport and powered by chemiosmosis using a proton gradient generated by redox reactions.

A series of membrane proteins that pass electrons through redox reactions and pump protons across a membrane, building a gradient used to make ATP; in photosynthesis, thylakoid carriers transfer electrons from PSII to PSI.