Cellular Respiration and Energy Metabolic Activities

This set of vocabulary flashcards covers the stages, chemical equations, locations, and key concepts of cellular respiration, including glycolysis, the Krebs cycle, the electron transport chain, and anaerobic conditions.

Cellular Respiration

The process by which energy is extracted from food molecules to obtain energy for cellular metabolic activities, summarized by the equation: $C_6H_{12}O_6 + 6 O_2 \rightarrow 6 CO_2 + 6 H_2O + \text{ATP}$.

Glycolysis

A 10-reaction process occurring in the cytosol, with or without $O_2$, that breaks down one molecule of glucose into two molecules of pyruvate, yielding 2 ATP and 2 NADH.

Substrate-level phosphorylation

The mechanism used in the energy payoff phase of glycolysis (steps 6-10) to transfer a phosphate group ($P_i$) from a compound to ADP to make ATP.

Oxidation of Pyruvate

An intermediate step in the mitochondrial matrix where pyruvate is oxidized into Acetyl Coenzyme A (CoA), producing $CO_2$ and reducing $NAD^+$ to NADH.

Pyruvate dehydrogenase

The enzyme involved in the intermediate step that oxidizes pyruvate into Acetyl Coenzyme A (CoA).

Krebs Cycle (TCA)

A series of 8 reactions in the mitochondrial matrix that processes Acetyl CoA; for two molecules of Acetyl CoA, it produces 2 ATP, 6 NADH, 2 $FADH_2$, and 4 $CO_2$.

Electron Transport Chain (ETC)

A series of electron carriers located in the inner mitochondrial membrane (cristae) where electrons from NADH and $FADH_2$ are transferred to oxygen, forming water of the formula $2 H + 2 e^- + 1/2 O_2 \rightarrow H_2O$.

Proton motive force

An imbalance of $H^+$ created by moving protons from the mitochondrial matrix to the intermembrane space during the electron transport chain.

ATP synthase

A protein complex that allows protons to move back into the matrix through an $H^+$ channel, coupling this movement to the formation of ATP from ADP and $P_i$.

Chemiosmosis

The process where the proton-motive force drives protons through ATP synthase to produce approximately 28-30 ATP and 6 $H_2O$.

Fermentation

A metabolic process occurring when no $O_2$ is present to act as the final electron acceptor, resulting in the regeneration of $NAD^+$ as electrons are dropped into a fermentation product.

Anoxia

A condition characterized by the total absence of available oxygen.

Hypoxia

A condition characterized by a low availability of oxygen.