AP BIO UNIT 3 CELLUAR RESPIRATION

Cellular respiration

The process that breaks down glucose to release energy and make ATP.

Overall equation of cellular respiration

The reaction: $\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + ATP$.

Oxidation

The process of losing electrons, as glucose is oxidized into carbon dioxide.

Reduction

The process of gaining electrons, as oxygen is reduced to form water.

Electron carriers

Molecules that carry high-energy electrons from glucose to the electron transport chain, e.g., NAD⁺ and FAD.

NADH

The reduced form of NAD⁺ that carries electrons to the electron transport chain.

FADH₂

The reduced form of FAD that carries electrons to the electron transport chain.

Mitochondrion structure

Organelles with an outer membrane, inner membrane, cristae, matrix, and intermembrane space.

Glycolysis

The first stage of cellular respiration occurring in the cytosol, splitting glucose into two pyruvate molecules.

Pyruvate oxidation

The second stage occurring in the mitochondrial matrix converting pyruvate into acetyl-CoA.

Krebs cycle

The third stage in the mitochondrial matrix that fully oxidizes acetyl-CoA to CO₂ and produces electron carriers.

Electron transport chain (ETC)

A series of proteins in the inner mitochondrial membrane that transfers electrons and pumps protons.

Chemiosmosis

The process where protons flow down their gradient through ATP synthase to produce ATP.

Proton gradient

The difference in proton concentration across the mitochondrial membrane that stores potential energy.

Substrate-level phosphorylation

The direct transfer of a phosphate group to ADP to form ATP, occurring in glycolysis and Krebs cycle.

Oxidative phosphorylation

The production of ATP using energy from electrons in the ETC to create a proton gradient.

Final electron acceptor

Oxygen, which combines with electrons and H⁺ to form water in the ETC.

Fermentation

A process that regenerates NAD⁺ from NADH and allows glycolysis to continue without oxygen.

Lactic acid fermentation

The conversion of pyruvate into lactate, regenerating NAD⁺ and occurring in muscle cells.

Alcohol fermentation

The conversion of pyruvate into ethanol and CO₂, regenerating NAD⁺ and occurring in yeast.

Anaerobic respiration

A process that uses an electron transport chain without oxygen.

Uncoupling protein 1 (UCP1)

A protein in brown fat that allows protons to return to the mitochondrial matrix, generating heat.