Explain sequence of events in cyclic photophosphorylation. Write a note on its significance.
Answers
Cyclic Photophosphorylation
We all are well aware of the complete process of photosynthesis. Yes, it is the biological process of converting light energy into chemical energy. In this process, the light energy is captured and used for converting carbon dioxide and water into glucose and oxygen gas. The complete process of photosynthesis is carried out into two processes:
Light reaction.
The light reaction takes place in the grana of the chloroplast. Here light energy gets converted to chemical energy as ATP and NADPH. In this very light reaction, the addition of phosphate in the presence of light or the synthesizing of ATP by cells is known as photophosphorylation.
Dark reaction.
While in the dark reaction, the energy produced previously in the light reaction is utilized to fix carbon dioxide into carbohydrates. The location where this happens in the stroma of the chloroplasts.
In this article, we will look at the complete process of photophosphorylation .i.e. the light reaction
Photophosphorylation is the process of synthesizing energy-rich ATP molecules by transferring the phosphate group into ADP molecule in the presence of light. These process may be either a cyclic process or a non-cyclic process
Cyclic Photophosphorylation
The photophosphorylation process which results in the movement of the electrons in a cyclic manner for synthesizing ATP molecules is called cyclic photophosphorylation.
In this process, plant cells just accomplish the ADP to ATP for immediate energy for the cells. This process usually takes place in the thylakoid membrane and uses Photosystem I and the chlorophyll P700.
During cyclic photophosphorylation, the electrons are transferred back to P700 instead of moving into the NADP from the electron acceptor. This downward movement of electrons from an acceptor to P700 results in the formation of ATP molecules.