Question

Choose the correct answers from the alternatives given :
Substrate-level phosphorylation takes place in

• A. Krebs cycle and the transition reaction
• B. glycolysis and the electron transport system
• C. electron transport system and the transition reaction
• D. glycolysis and the Krebs cycle

Answer 1

The correct option is D glycolysis and the Krebs cycle

• Substrate level phosphorylation is the reaction where ATP is formed by the phosphate molecule that is taken from the substrate in the reaction.
• In glycolysis during the conversion of 1,3 bisphosphoglyceric acid to 3 phosphoglyceric acid and coversion of phosphophenol to pyruvic acid; one molecule of ATP is formed during each reaction.
• In kerb cycle during the formation of succinic acid from succinyl CoA GTP is formed which is a substrate level phosphorylation, afterwards this GTP is converted to ATP in a coupled reaction.
• No substrate level phosphorylation takes place in oxidative phosphorylation or ETS
• Therefore the answer 'glycolysis and the Krebs cycle' is correct.