Question

1. summarize what roles do adp and atp play in the light - dependent and light - independent reactions?

Explanation:

• Light - dependent reactions:
• Light energy is used to split water (photolysis). Electrons from this process are passed through an electron transport chain. As electrons move through the chain, protons (\(H^+\)) are pumped across a membrane, creating a proton gradient.
• ADP (\(Adenosine\ diphosphate\)) combines with an inorganic phosphate (\(P_i\)) in a process called chemiosmosis (using the energy from the proton gradient) to form ATP (\(Adenosine\ tri - phosphate\)). So, in light - dependent reactions, ADP is a reactant that gets converted to ATP, which stores energy.
• Light - independent reactions (Calvin cycle):
• ATP, which was generated in the light - dependent reactions, donates its phosphate group (and the energy associated with it) to molecules in the Calvin cycle. For example, in the reaction where 3 - phosphoglycerate is converted to 1,3 - bisphosphoglycerate, ATP is used.
• When ATP donates a phosphate group, it is converted back to ADP. So, in the light - independent reactions, ATP is an energy donor that gets converted to ADP, and ADP can then be recycled back to the light - dependent reactions to be converted to ATP again.

Answer:

In light - dependent reactions, ADP is converted to ATP (which stores energy) using the energy from the electron transport chain and chemiosmosis. In light - independent reactions (Calvin cycle), ATP donates its energy (by converting to ADP) to drive reactions like the conversion of 3 - phosphoglycerate to 1,3 - bisphosphoglycerate. ADP is then recycled back to the light - dependent reactions to be re - energized to ATP.