Cellular Biology

The cell is the basic structural, functional, and biological unit of all known organisms.

Cellular Respiration

The set of metabolic reactions that convert chemical energy from oxygen molecules or nutrients into adenosine triphosphate (ATP).

The Stages

1. Glycolysis: Occurs in the cytoplasm. Converts glucose into pyruvate, yielding 2 ATP and 2 NADH.
2. Krebs Cycle (Citric Acid Cycle): Occurs in the mitochondrial matrix. Oxidizes acetyl-CoA to CO₂, yielding 2 ATP, 6 NADH, and 2 FADH₂ per glucose molecule.
3. Electron Transport Chain: Occurs in the inner mitochondrial membrane. Uses NADH and FADH₂ to pump protons, creating an electrochemical gradient that drives ATP synthase. Yields ~26-28 ATP.

Total theoretical yield: ~30-32 ATP per molecule of glucose.