Difference between Photosystem I and Photosystem II (PSI vs PSII)

Photosynthesis takes place in two steps: Light reaction and Dark reaction. Light reaction occurs in the grana of chloroplast. The chlorophyll absorbs the light energy. Hence the chlorophyll is called a photosystem or pigment system. Chlorophylls are of different types and they absorb different wavelengths of light. Accordingly chlorophylls exist two photosystems, namely photosystem I (PS I) and photosystem II (PS II).

Both photosystem (PS I and PS II) are affected by light with wavelengths shorter than 680nm (nanometer), while photosystem I is affected by light with wavelengths longer than 680nm.
Photosystem I and Photosystem II
Photosystem I includes the following pigments: Chlorophyll b, Chlorophyll -a 670, Chlorophyll -a 680, Chlorophyll -a 695, Chlorophyll -a 700 or P700, Carotenoids.
In photosystem I, P700 form of chlorophyll a is the active reaction centre.

Photosystem II includes the following pigments: Chlorophyll b, Chlorophyll - a 660, Chlorophyll -a 670, Chlorophyll -a 680 or P680, Chlorophyll -a 695, Chlorophyll - a 700 or P700, Phycobilins, Xanthophylls.
In photosystem II, P680 form of chlorophyll a is the active reaction centre.
Photosystem I and Photosystem II
Photosystem I (PS I)
Photosystem II (PS II)
PS I is located at the outer surface of the grana thylakoid membrane. PS II is located at the inner surface of the grana thylakoid membrane.
The photocentre is P700. The photocentre is P680.
Pigments absorb longer wavelengths of light (>680nm). Pigments absorb shorter wavelengths of light (<680nm).
Participates in cyclic as well as non cyclic photophosphorylation. Participates only in non cyclic photophosphorylation.
It is not associated with photolysis of water. It is associated with photolysis of water.
Main function is ATP synthesis. Main functions are ATP synthesis and hydrolysis of water.
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2 comments:

Anonymous said...

Thankz diz is really helpfull..

Anonymous said...

Helpful thanks

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