Question

Differentiate between oxidative phosphorylation and photophosphorylation.

Answer 1

Oxidative phosphorylation occurs in aerobic cells to generate energy through metabolism. Photophosphorylation is the process of capturing solar energy and converts to chemical energy.

Complete answer:
- Phosphorylation is the synthesis of ATP from ADP during the chemical reactions. Both oxidative and photo-phosphorylation deals with generation of energy. Both processes involve ETC for transport of electrons and ATP is synthesised by proton motive force. It is well explained as chemiosmotic theory of ATP synthesis.

- The degradation of carbohydrates, fats, and amino acids converge at the final stage of cellular respiration, in which the energy of oxidation drives the synthesis of ATP from reducing equivalents as NADH.

- In photophosphorylation, solar energy is captured by chlorophyll pigments and converts it to chemical energy in the form of ATP. But oxidative phosphorylation is differentiated from photophosphorylation in following manner as

Points	Oxidative phosphorylation	Photophosphorylation
Site	It occurs in mitochondria	It occurs in chloroplast
Process chemistry	It involves the reduction of O2 to H2O with electrons donated by NADH and FADH2.O2 will be the final electron acceptor.	It involves the oxidation of H2O to O2, with NADP. NADP acts as a final electron acceptor.
Occurrence	It occurs in aerobic cells.	It occurs in photosynthetic cell
Requirement of light	It occurs well in light and dark conditions.	It occurs only in light condition
Energy	Chemical energy is converted into ATP	Light energy is converted into ATP

Note: Oxidative phosphorylation occurs in mitochondria and converts chemical energy into ATP. Photophosphorylation occurs in chloroplast and converts solar energy into ATP.