Cellular Respiration: Pathways and Processes

Glycolysis

Phase 1 in the path of making ATP from glucose, involving the breakdown of a 6-carbon sugar to two 3-carbon molecules in the cytoplasm of all living cells.

Aerobic Respiration

Process where the carbon source is completely converted to carbon dioxide, involving the conversion of pyruvate to acetyl-CoA, followed by the Krebs Cycle, occurring in mitochondria of eukaryotes.

Mitochondrion

Organelle responsible for ATP generation, with an outer membrane, inner membrane, matrix, and intermembrane space.

Krebs Cycle

Also known as the Citric Acid Cycle, a series of reactions where acetyl-CoA is oxidized to carbon dioxide and ATP, NADH, and FADH2 are produced.

Aerobic respiration

Requires oxygen for energy production

Electron Transport Chain

Series of protein complexes transferring electrons, creating a proton gradient

NADH

Donates electrons to the first carrier in the Electron Transport Chain

Proton gradient

Result of energy release from electron transfer, used to pump protons

Oxygen

Final electron acceptor in the Electron Transport Chain

Water

Formed when oxygen combines with electrons and protons

FADH2

Electron carrier in the Electron Transport Chain, contributes less to proton pumping

ATP production

Generated from breakdown of glucose, theoretical calculation from glycolysis, TCA cycle, and ETC

Oxidative Phosphorylation

Final step in glucose oxidation, involving ETC and ATP synthase

Substrate-Level Phosphorylation (SLP)

Direct ATP synthesis in glycolysis and TCA cycle

Low-carb diets

Alternative ATP production pathways when carbohydrates are limited

Anaerobic conditions

Conditions where aerobically-respiring cells switch to anaerobic pathways

Fermentation

A metabolic process that produces chemical changes in organic substrates through the action of enzymes, producing energy without the involvement of oxygen.

NAD+ Regeneration

The process of restoring NAD+ levels by transferring electrons from NADH back to NAD+ to sustain glycolysis.

Ethanol

A fermentation product resulting from the conversion of pyruvate, commonly found in alcoholic beverages.

Lactic Acid

A fermentation product formed by the conversion of pyruvate, often found in sour milk products.

Allosteric Regulation

Regulation of enzyme activity through the binding of molecules to sites other than the active site, altering the enzyme's conformation and activity.

Positive Regulator

A molecule that binds to an enzyme and increases its activity, promoting the catalysis of a reaction.

Negative Regulator

A molecule that binds to an enzyme and decreases its activity, inhibiting the catalysis of a reaction.

Feedback Inhibition

A mechanism in which the end product of a metabolic pathway inhibits an enzyme involved in an earlier step of the pathway, regulating the pathway's activity.