BIOLOGY / STUDY GUIDE
Cellular Respiration
How cells turn glucose into usable energy
01Overview
Cellular respiration converts the chemical energy in glucose into ATP. Its main stages include glycolysis, the citric acid cycle, and oxidative phosphorylation. These stages transfer energy from glucose into a form cells can use for cellular work.
Glucose + oxygen → carbon dioxide + water + ATP
02Key Concepts
ATPEnergy currencyTransfers energy to power cellular work.
Cells use ATP for transport, biosynthesis, and movement.
Why it matters: ATP supplies usable energy for the work that keeps cells functioning.
GlycolysisCytosolSplits glucose into two pyruvate; yields 2 net ATP.
Glycolysis happens in the cytosol and also produces 2 NADH.
Why it matters: It starts the breakdown of glucose and supplies pyruvate for the next stage.
Oxidative phosphorylationInner mitochondrial membraneUses a proton gradient to drive ATP synthesis.
Electron transport establishes the gradient across the inner mitochondrial membrane. ATP synthase uses that gradient.
Why it matters: It produces most of the ATP in aerobic respiration.
03Outline
- 1Break down glucose
- Glycolysis → pyruvate
- 2Extract high-energy electrons
- Pyruvate oxidation → citric acid cycle
- 3Make most of the ATP
- Electron transport → chemiosmosis
04Key Points
- Oxygen is the final electron acceptor.
- Most ATP comes from oxidative phosphorylation.
- Carbon dioxide is released before the electron transport chain.
05Common Confusions
Breathing ≠ cellular respiration
Breathing exchanges gases; respiration releases energy inside cells.
Plants respire, too
Photosynthesis stores energy; respiration makes it available.