Notes from NEET topper
PHOTOPHOSPHORYLATION:
Photophosphorylation is a process in photosynthesis where light energy is converted into ATP (adenosine triphosphate), a form of chemical energy that is usable by the cell. There are two main types of photophosphorylation: cyclic and non-cyclic.
- Cyclic Photophosphorylation:
- In cyclic photophosphorylation, the electrons are cycled back to the original chlorophyll molecule.
- This process only involves Photosystem I.
- It produces ATP but does not produce NADPH or oxygen.
- The process starts with a photon hitting the pigment in the photosystem, which results in the transfer of an electron to a higher energy state.
- The high-energy electron is passed along a series of proteins in the thylakoid membrane (electron transport chain).
- As the electron passes through the electron transport chain, its energy is used to pump protons across the thylakoid membrane, creating a proton gradient.
- The electron eventually cycles back to the photosystem.
- The proton gradient is used by ATP synthase to generate ATP.
