Question

In the light reactions of photosynthesis, a proton gradient is generated which drives ATP synthesis. Where do protons become concentrated in the chloroplast?

Answer 1

In the light reactions of photosynthesis, protons become concentrated in the thylakoid lumen of the chloroplast. ATP synthase uses the proton gradient to synthesize ATP. ATP is an energy carrier used for various cellular processes.

Step-by-step explanation:

In the light reactions of photosynthesis, protons become concentrated in the thylakoid lumen of the chloroplast. The movement of electrons through the chloroplast electron transport chain creates a proton gradient, similar to the one found in the inner mitochondrial membrane during cellular respiration. This proton gradient is formed as protons are pumped from the stroma into the thylakoid lumen. As a result, the thylakoid lumen becomes more acidic, or has a lower pH, compared to the stroma.

ATP synthase, a transmembrane enzyme, uses chemiosmosis, the movement of protons down their electrochemical gradient, to synthesize ATP. The flow of protons through ATP synthase powers the addition of a phosphate group to ADP, producing ATP. ATP is an important energy carrier used for various cellular processes, including the formation of sugar molecules during the second stage of photosynthesis.