Substrate-level phosphorylation

Definition

Substrate-level phosphorylation is a metabolic process for generating ATP by the direct transfer of a phosphate group to ADP from an intermediate substrate. This occurs in the cytoplasm during glycolysis and in the mitochondrial matrix during the Krebs cycle.

5 Must Know Facts For Your Next Test

1. It directly generates ATP without the use of an electron transport chain.
2. Occurs in both glycolysis and the Krebs cycle.
3. Involves enzyme-catalyzed reactions where a high-energy phosphate group is transferred to ADP.
4. Does not require oxygen, making it important during anaerobic conditions such as fermentation.
5. Produces less ATP compared to oxidative phosphorylation.

Review Questions

• Where does substrate-level phosphorylation occur within a cell?
• How does substrate-level phosphorylation differ from oxidative phosphorylation?
• What role does substrate-level phosphorylation play in anaerobic conditions like fermentation?

Related terms

Glycolysis: A metabolic pathway that breaks down glucose into pyruvate, producing ATP and NADH.

Fermentation: A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

Oxidative Phosphorylation: A metabolic pathway used to generate ATP using energy derived from electrons transferred through an electron transport chain.