Name: Kranz Anatomy - The Ring of Cells
Uploaded: 2019-07-19
Duration: 5 min 1 s
Description: Let's learn about the characteristic features of certain plants responsible for the process of photosynthesis and photorespiration.

Question

Where does cyclic photophosphorylation take place in the leaves? Why is this process called cyclic? Describe cyclic photophosphorylation.

Accepted Answer

The cyclic photophosphorylation takes place in the leaves at the non-appressed part of the grana of chloroplast of palisade mesophyll cells. This process is called cyclic because the electron released from the reaction center (P700) after getting the photons comes back to the reaction center after releasing its energy. The cyclic photophosphorylation:

The specific light intensity falls over the reaction center, the electron is released from the reaction center made up of the Chl-a. This electron reaches to various electron carriers like Ferridoxin, PQ, Cyt bf, PC, etc which get reduced after accepting the electron and then again get oxidized as soon as they release the electrons. During the reduction-oxidation of the carrier molecules, some carrier molecules like PQ created a proton gradient due to which the protons(H⁺) get pumps into the thylakoid lumen from the stroma. This proton causes acidic conditions inside the lumen. So to pump them back to the stroma, a transport protein called ATP synthase is present in the thylakoid membrane that pumps out the protons from the lumen to the stroma. When the proton passes through it, ATP is synthesized. Example: Green plants. Halophile bacteria also perform photophosphorylation.

Where does cyclic photophosphorylation take place in the leaves? Why is this process called cyclic? Describe cyclic photophosphorylation.

Important Questions on Photosynthesis in Higher Plants

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