Question

A) Define “substrate-level phosphorylation." (One clear complete sentence will work as an answer.) B) The reaction ADP + Pi → ATP is highly endergonic. In the case of substrate-level phosphorylation, where does the energy required for ATP synthesis come from? (Not the sun. I mean most immediately in the phosphorylation reaction itself.) C) Define "oxidative phosphorylation.” (One clear complete sentence will work as an answer.)

Be CLEAR and CORRECT

Answer 1

1. Substrate Level Phosphorylation:
Substrate Level Phosphorylation is a reaction in which a higher energy substrate is converted to a lower energy substrate for the formation of ATP or GTP. The chemical energy released, (Gibb's free energy) during the conversion of high energy substrate to low energy substrate is used during the ATP/GTP formation by transfer a phosphoryl group.

2. The energy during the formation of ATP from ADP + Pi during substrate level phosphorylation reaction comes from release of Gibb's free energy by the breakdown of a high energy substrate into a low energy substrate.
Example: Phosphoenolpyruvate is a high energy molecule which is broken down to form Pyruvate and the energy formed during this endergonic reaction is used to form an ATP molecule along with the product.

3. Oxidative Phosphorylation is a process in which nutrients are oxidized by cells with the help of enzymes which results in the release of molecular oxygen's chemical energy which is then used for the production of ATP.
The electrons are transferred from NADH/ FADH2 to Oxygen by a chain of electron carriers.