Question

what does 'PGA' stand for in Calvin cycle​

Answer 1

• Calvin cycle is the dark phase or synthetic phase of photosynthesis. It uses the energy obtained from light reaction.

• Calvin cycle was first described by the scientist Melvin Calvin.

• It takes place in all photosynthetic plants.

• It is the only process occuring in mesophyll cells of C3 plants. Example: Potoato, rice, wheat, etc,.

• Calvin cycle is also called C3 cycle because , the first stable product formed is a three carbon compound.

• The three carbon compound is PGA (Phospho Glyceric Acid)

• The first step in calvin cycle is carbon fixation or carboxylation. It is the most crucial step. It does not require energy for carbon fixation.

• When carbon dioxide is fixed by five carbon Rubisco enzyme, it forms two moles of three carbon compound PGA.

• The second step is carbon reduction.

• The reduction step requires 2 moles of ATP and 2 moles of NADPH.

• The last step is regeneration, in which the Rubisco enzyme is regenerated using single molecule of ATP.

• Totally the calvin cycle requires 3 moles of ATP and 2 moles of NADPH.