Cellular respiration is the set of metabolic reactions and processes that take place in cells to convert chemical energy into ATP.
Steps of cellular respiration:
- glycolysis
- preparatory reaction
- Krebs cycle
- electron transport chain
glycolysis
Glycolysis, (also called anaerobic respiration) is the part of cellular respiration that doesn’t require oxygen, converting glucose into pyruvate while releasing free energy used to form ATP and NADH.
Occurs in the cytoplasm.
Input:
- 2 ATP
- 1 glucose
Output: - 4 ATP per glucose
- pyruvate
Krebs cycle
The Krebs cycle (also the citric acid cycle) is a series of reactions in cellular respiration used to release the energy stored in nutrients.
Occurs in the mitochondrial matrix.
Pyruvate is converted to acetyl CoA, which enters the cycle.
Input:
- 2 acetyl CoA (converted from pyruvate)
- 6 NAD⁺
- 2 FAD
Output:
- 4 carbon dioxide
- 2 ATP
- 6 NADH
- 2 FADH₂
electron transport chain
An electron transport chain (ETC) is a series of protein complexes and molecules that transfer electrons from electron donors to electron acceptors via redox reactions.
Occurs in the mitochondrion cristae (foldings in the middle).
Input:
- oxygen
- 10 NADH
- 2 FADH₂
Output:
- water
- 26 to 28 ATP
- NAD⁺
- FAD