What happens during cyclic electron flow in photosynthesis?
By Rachel Newton
What happens during cyclic electron flow in photosynthesis?
In cyclic electron flow (CEF), electrons are recycled around photosystem I. As a result, a transthylakoid proton gradient (ΔpH) is generated, leading to the production of ATP without concomitant production of NADPH, thus increasing the ATP/NADPH ratio within the chloroplast.
What is the cyclic flow of electrons?
In cyclic electron flow, electrons are repeatedly cycled though PSI. After an electron in PSI is excited and passed to ferredoxin, it is passed back to the cytochrome complex in the first part of the electron transport chain.
What does cyclic electron flow produce?
Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700) but not photosystem II (P680). This process produces no NADPH and no O2, but it does make ATP. This is called cyclic photophosphorylation.
Is cyclic electron flow Photoprotective?
Cyclic electron flow (CEF) has been documented as a crucial mechanism for photoprotection in Arabidopsis and tobacco. We hypothesized that CEF plays an important role in protecting photosystem I (PSI) and photosystem II (PSII) against drought stress for resurrection plants.
What is cy in photosynthesis?
They are captured by the antenna complex and transferred to the Photosystem I reaction center, which contributes two high energy electrons to the primary electron receptor. They are passed to ferrodoxin (Fd), an iron containing protein which acts as an electron carrier.
What’s the difference between cyclic and noncyclic electron flow?
Cyclic photo-phosphorylation in photosynthesis light dependent reaction leads to the formation of ATP and NADPH, and the electrons go from water to PSII to PSI and eventually to NADPH. In non-cyclic photo-phosphorylation only some ATP is produced and the electrons go from PSII to PSI and back again.
Why is the cyclic pathway so important?
With the cyclic pathway, plants can save some time and energy. Since photosystem I is accepting electrons that are returned to it, it is not accepting electrons from the previous electron transport chain. Therefore, the first electron transport chain will be backed up, which means that photolysis will not occur.
What is the difference between cyclic electron flow and noncyclic electron flow?
