Briefly explain the following terms:
Photophosphorylation
Topic: Photophosphorylation
Answer
PHOTOPHOSPHORYLATION is the formation of the energy-rich compound ATP (adenosine triphosphate) from ADP (adenosine diphosphate) and inorganic phosphate, IN THE PRESENCE OF LIGHT, during the light reaction of photosynthesis.
The word defines itself: PHOTO (light) + PHOSPHORYLATION (the adding of a phosphate group). Adding a third phosphate to ADP makes ATP, using light energy.
THE TRAP is PHOTOLYSIS, which also begins with PHOTO and also occurs in the light reaction. But -LYSIS means SPLITTING, and photolysis is the splitting of WATER.
The two light-reaction events side by side: PHOTOLYSIS — water is split; oxygen released; hydrogen picked up by NADP PHOTOPHOSPHORYLATION — ADP + phosphate becomes ATP Read the SECOND half of the word, not the first.
Both products, NADPH₂ and ATP, are then carried into the DARK reaction to build glucose — which is how the two stages are linked.