What is Aerobic Cellular Respiration?
Aerobic cellular respiration is the process cells use to break down glucose in the presence of oxygen, releasing energy stored as ATP. It occurs in four stages: glycolysis, pyruvate oxidation, the Krebs cycle, and oxidative phosphorylation.
Aerobic respiration is the oxygen-dependent breakdown of glucose into CO2 and water, producing roughly 30-32 ATP per glucose molecule through glycolysis, the Krebs cycle, and the electron transport chain.
- 1↓GlycolysisIn the cytoplasm, glucose splits into 2 pyruvate, netting 2 ATP and 2 NADH.
- 2↓Pyruvate OxidationEach pyruvate enters the mitochondrion and is converted to acetyl-CoA, releasing CO2 and forming NADH.
- 3↓Krebs CycleAcetyl-CoA is fully oxidized in the mitochondrial matrix, producing 2 ATP, 6 NADH, and 2 FADH2 per glucose (2 turns).
- 4Electron Transport Chain & Oxidative PhosphorylationNADH and FADH2 donate electrons to the inner membrane chain, driving chemiosmosis that produces roughly 26-28 ATP.
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Step-by-step worked examples
One glucose molecule is fully broken down through glycolysis, the Krebs cycle, and oxidative phosphorylation. Roughly how much net ATP does the cell gain?
Glycolysis nets 2 ATP directly. The Krebs cycle nets 2 more ATP directly (from 2 turns per glucose). Oxidative phosphorylation from the resulting NADH/FADH2 yields roughly 26-28 ATP, for a total of about 30-32 ATP per glucose.
A muscle cell processes 5 glucose molecules aerobically. Using an estimate of 30 ATP per glucose, how much total ATP is produced?
ATP per glucose ≈ 30. Total ATP = 30 × 5 glucose molecules. Total ATP = 150 ATP molecules.
During glycolysis, 2 ATP are invested and 4 ATP are generated per glucose. What is the net ATP yield of glycolysis alone?
Net ATP = ATP generated − ATP invested. Net ATP = 4 − 2. Net ATP = 2 ATP per glucose.
Flashcards
Quick quiz
Q1.Where does glycolysis take place?
Q2.Which stage produces the most ATP in aerobic respiration?
Q3.What is the final electron acceptor in aerobic respiration?
Q4.Approximately how much net ATP is produced per glucose molecule in aerobic respiration?
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Common mistakes
All ATP from respiration comes from glycolysis. — Correct: Most ATP (about 26-28 of ~30-32) comes from oxidative phosphorylation, not glycolysis.
The Krebs cycle directly requires oxygen to run its reactions. — Correct: The Krebs cycle itself doesn't use O2 directly, but it depends on NAD+/FAD supplied by the O2-dependent electron transport chain.
Glycolysis happens inside the mitochondria. — Correct: Glycolysis happens in the cytoplasm; only later stages occur inside the mitochondria.
Aerobic respiration produces glucose. — Correct: Aerobic respiration breaks glucose DOWN to release energy; it doesn't produce glucose.
FAQ
What is aerobic cellular respiration?
It's the oxygen-dependent process cells use to break down glucose into CO2 and water, producing roughly 30-32 ATP per glucose.
What is the formula for aerobic respiration?
C6H12O6 + 6O2 → 6CO2 + 6H2O + ~30-32 ATP.
What are examples of aerobic respiration in the body?
Muscle cells during steady exercise, brain neurons, and heart cells all rely heavily on aerobic respiration for continuous ATP supply.
How do you calculate the ATP yield of aerobic respiration?
Multiply the number of glucose molecules by roughly 30 ATP, combining the yields of glycolysis, the Krebs cycle, and oxidative phosphorylation.