04.05.2024

Hi everyone today i am going to explain nonphotochemical quenching which is a. photo protective method for plants to survive,. in less than 5 minutes, i hope you enjoy this video.. Photosynthesis is the process used by plants to convert. light energy into chemical energy that can help for the plant. to perform various cellular activities,. however excess light energy could be harmful. for plants light is absorbed by the light harvesting pigment protein. complexes, associated with the reaction centers in. the leaves of the plants.. Chlorophyll molecules are bound to the chlorophyll binding proteins. in the light harvesting complexes and on absorption of light chlorophyll. molecules can go from the ground state to the. singlet excited state this singlet excited form, of the. chlorophyll molecules, it needs to dissipate energy.

To come back to the ground state. First it can do so by converting the singlet chlorophyll state to a triplet chlorophyll state, this triplet chlorophyll state can then excite the oxygen molecule converting it into singlet state oxygen radical that can form reaction oxygen species which is harmful for plants. However in doing so the triplet chlorophyll state can then come back to the ground state of the chlorophyll molecule. The second state for relaxing back from the singlet chlorophyll state is by emitting light as fluorescence. The third way is to spend the energy into photosynthetic reactions and this process is known as photochemistry.

The fourth way by which the singlet state chlorophyll molecule can. relax back into the ground state is known as nonphotochemical quenching. by which the energy can be dissipated as heat.. As there is no photochemistry involved in it that's why it's called. nonphotochemical quenching. Based on the relaxation rate of the. chlorophyll molecule this process can be divided. into three components depending upon the rate of relaxation.. First is the energy dependent component or the pH. dependent component also referred to as qE,. the second is the component that is dependent. upon state transition by which the light harvesting complexes can get. uncoupled from the photo systems and this component is referred to as. qT and the third component is the process that is related to the. photo inhibition of the photo synthesis and is referred to as.

QI, in the description below i will link the paper from which you can learn about this various processes much more easily for more information. NPQ or nonphotochemical quenching is involved with conformational changes in the light harvesting complexes of PSII due to absorption of light high absorption leads to increase in the hydrogen ion in lumen which decreases the pH and causes the protonation of the PsbS subunit of the PSII also violaxanthin deepoxide enzyme is activated that converts viola- xanthine to zeaxanthin, only violaxantine is able to transport photons to chlorophyll a this is a way by which the photon transfer is then hampered and the plants are protected.

NPQ saves the plants from further photon transfer due to presence. of excessive light that could hamper plants. and thus save the plants from future damage.. I hope you like this video and if you have enjoyed this video. please put a thumbs up and subscribe to my channel. have a good day bye