How is the production of ATP in the electron transport chain similar to the production of ATP during the light dependent reactions of photosynthesis?
The correct answer and explanation is :
Correct Answer:
The production of ATP in the electron transport chain (ETC) of cellular respiration is similar to ATP production during the light-dependent reactions of photosynthesis because both processes use chemiosmosis to generate ATP. In both cases, an electron transport chain creates a proton gradient across a membrane, which powers ATP synthase to produce ATP from ADP and inorganic phosphate.
Explanation (300 words)
ATP production in both cellular respiration and photosynthesis involves an electron transport chain and chemiosmosis. Despite occurring in different organelles (mitochondria for cellular respiration and chloroplasts for photosynthesis), both systems follow a similar mechanism.
In the electron transport chain of cellular respiration, electrons from NADH and FADH₂ are transferred through protein complexes in the inner mitochondrial membrane. As electrons move through the ETC, protons (H⁺) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient. The accumulation of H⁺ ions generates a high concentration outside the inner membrane. These protons then flow back into the matrix through ATP synthase, a protein that uses this movement to convert ADP into ATP.
Similarly, in the light-dependent reactions of photosynthesis, electrons excited by sunlight in Photosystem II travel through an electron transport chain located in the thylakoid membrane. This movement powers proton pumps that transport H⁺ ions from the stroma into the thylakoid lumen, creating a proton gradient. The return flow of protons through ATP synthase into the stroma drives the conversion of ADP into ATP.
In both systems, the proton motive force generated by the movement of electrons through the ETC is essential for ATP production. However, the energy source differs: cellular respiration relies on energy from glucose, while photosynthesis uses sunlight. Despite this difference, the fundamental mechanism—chemiosmosis—remains the same.