Question

Describe the roles of ADP in the enzyme reactions of the Krebs Cycle and the respiratory (electron transport) chain/chemiosmosis..

A) Substrate for ATP synthase.
B) Regulatory molecule.

Answer 1

ADP acts as both a substrate for ATP synthase and a regulatory molecule in enzyme reactions of the Krebs Cycle and the respiratory chain/chemiosmosis.

Step-by-step explanation:

ADP plays two important roles in the enzyme reactions of the Krebs Cycle and the respiratory (electron transport) chain/chemiosmosis:

1. Substrate for ATP synthase: ADP is converted to ATP by the energy released during the electron transport chain in the mitochondrial respiration. This conversion occurs when ADP binds to ATP synthase, and a phosphate is added to ADP to form ATP.
2. Regulatory molecule: ADP and ATP levels regulate the rate of electron transport through the pathway. A higher concentration of ADP in the cell indicates greater ATP usage, triggering the cell to slow down the electron transport chain. Conversely, as ATP usage decreases and the concentration of ADP decreases, ATP begins to build up in the cell, triggering the cell to speed up the electron transport chain.