Chapter 5 Study Guide: Cell Respiration and Metabolism

Flashcards for Cell Respiration and Metabolism

Metabolism

All the reactions in the body that involve energy transformation.

Catabolism

Breaks down larger organic molecules and releases energy; primary source of energy for making ATP.

Anabolism

Makes larger molecules and requires input of energy; includes body’s large energy-storage molecules including glycogen, fat and protein; also known as endergonic reactions.

Glycolysis

The breakdown of glucose (C6-H12-O6) for energy, begins with the metabolic pathway in the cytoplasm.

Gluconeogenesis

The metabolic pathway in which glucose is synthesized from non-carbohydrate precursors such as lactate, glycerol, and certain amino acids.

Cori Cycle

Couples muscle and liver metabolism under anaerobic conditions, involving the conversion of pyruvate to lactate in muscle, transport to the liver, and conversion back to glucose.

Krebs Cycle

Occurs in mitochondria, where pyruvate is converted to acetyl-CoA, which then enters a cycle of reactions to produce ATP, CO2, NADH, FADH2, and GTP.

Electron Transport Chain (ETC)

Located in the inner mitochondrial membrane and consists of complexes I–IV plus mobile carriers; NADH donates electrons to Complex I; FADH₂ to Complex II; ultimately reduces O₂ to water and creating a proton gradient.

Oxidative Phosphorylation

Uses the proton-motive force to drive ATP synthesis via ATP synthase (Complex V).

Glycogenolysis

Breakdown Glycogen → glucose-1-phosphate → glucose-6- phosphate → free glucose (via glucose-6-phosphatase in liver), released into circulation.

Ketone bodies

When acetyl-CoA accrual exceeds TCA capacity (e.g., starvation, diabetes), the liver converts it into ketone bodies: acetoacetate, β-hydroxybutyrate, and acetone.

Lactate Pathway

When oxygen is not available in sufficient amounts, the NADH(+H+) produced in glycolysis is oxidized in the cytoplasm by donating its electrons to pyruvate.