Question

what are three ways the proton gradient in the chloroplast is maintained? Describe the pathway of electrons from the beginning of photosynthesis to the end.

Answer 1

Answer:

1. Electron transfer is mediated through photosystem I and photosystem II and also through the bf complex, which allows:

i. release of H⁺ into the thylakoid lumen

ii. take up of H⁺ from the stroma

iii. impermeability of the thylakoid membrane to protons

These help in maintaining a proton gradient in the chloroplast.

2. The sequence of electrons during photosynthesis have been given schematically below:

Photosynthetic Active Radiation (400 - 700 nm)   P680 e^- pheophytin Q_A Q_B Plastoquinone Cytochrome bf complex plastocyanin P700 Fe-S proteins Ferredoxin NADP⁺ NADPH

Answer 2

Answer:

1. Electron transfer is mediated through photosystem I and photosystem II and also through the bf complex, which allows:

i. release of H⁺ into the thylakoid lumen

ii. take up of H⁺ from the stroma

iii. impermeability of the thylakoid membrane to protons

These help in maintaining a proton gradient in the chloroplast.

2. The sequence of electrons during photosynthesis have been given schematically below:

Photosynthetic Active Radiation (400 - 700 nm)   P680 e^- pheophytin Q_A Q_B Plastoquinone Cytochrome bf complex plastocyanin P700 Fe-S proteins Ferredoxin NADP⁺ NADPH