How it works
The first chart follows the carbon of glucose through the steps of cellular respiration until it leaves as carbon dioxide. The second follows the energy along the inner membrane of the mitochondrion to ATP.
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Read each chart along its arrows
On the first chart the dots count carbons: six in glucose, three in each pyruvate, two in acetyl CoA, one in carbon dioxide. Glycolysis happens in the cytoplasm; everything after it happens inside the mitochondrion. On the second chart NADH and FADH₂ bring electrons to the chain. The chain pumps hydrogen ions across the membrane, and they flow back through ATP synthase, which makes ATP. Oxygen takes the electrons at the end and becomes water.
- Large boxes are stages; rounded boxes are molecules.
- Oxygen is used at one place only: the end of the electron transport chain.
Questions and answers
What are the steps of cellular respiration in order?
Glycolysis, pyruvate oxidation, the citric acid cycle, then oxidative phosphorylation: the electron transport chain and ATP synthase. Glucose goes in at the start; carbon dioxide, water and ATP come out.
Where does each stage of cellular respiration happen?
Glycolysis happens in the cytoplasm. Pyruvate oxidation and the citric acid cycle happen in the matrix of the mitochondrion. The electron transport chain and ATP synthase sit in its inner membrane.
What is the equation for cellular respiration?
Glucose and oxygen give carbon dioxide, water and energy: C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + energy. The energy is used to make ATP.
Why does cellular respiration need oxygen?
Oxygen is the final electron acceptor. It takes the electrons at the end of the electron transport chain and, with hydrogen ions, forms water.