10 Crucial Difference between Photosystem I and Photosystem II with Table

calendarJun 25, 2022 · 3 min read  ·
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What is the difference between photosystem I and photosystem II?

Photosynthesis takes place in both light stage and dark stages. The reaction normally takes place in the grana of the chloroplast. The chlorophyll absorbs the light energy to foster photosynthesis. The chlorophyll is what is known as the photosystem. There are different types of chlorophyll and they absorb different types of light wavelength.

The common types of chlorophyll are photosystem I and photosystem II. The discussion provides a detailed insight into the core difference between photosystem I and photosystem II in a tabular form.

Difference between Photosystem I and Photosystem II

What Is Photosystem I?

Photosystem I refers to the collection of the green pigment that occurs on the outer surface of the thylakoid membrane. These pigments mostly absorb the wavelength of about 70nm. It is responsible for facilitating the final stage of light reaction. The core of PSI is made up of psaA and psaB subunits.

What Is Photosystem II?

Photosystem II refers to the collection of chlorophyll pigment that occurs in the inner grana of the thylakoid membrane. These pigments mostly absorb the wavelength of about 680nm. It is responsible for catalyzing the first stage of light reaction. The core of PSII consists of D1 and D2 subunits.

Comparison Chart: Photosystem I vs Photosystem II

Basic TermsPhotosystem IPhotosystem II
LocationThe outer surface of the thylakoid membraneThe inner surface of grana of the thylakoid membrane
PhotocenterP700P680
Absorbing WavelengthPigments absorb longer wavelengths of lightPigments absorb shorter wavelengths of light
PhotophosphorylationOccur in both cyclic and non-cyclic photophosphorylationOccur in cyclic photophosphorylation.
PhotolysisDo not happenTend to occur
Core FunctionSynthesis of NADPHHydrolysis of water and synthesis of ATP
Electron ReplacementReleased high energy electrons are replaced by the releasing energy of photolysis.Released high energy electrons are replaced by the electrons released from photosystem II.
PigmentsConsists of chlorophyll B, chlorophyll A-670, Chlorophyll A-680, chlorophyll A-695, chlorophyll A-700 and carotenoids.Consists of chlorophyll B, chlorophyll A-660, chlorophyll A-670, chlorophyll A-680, chlorophyll A-695, chlorophyll A-700, phycobilins and xanthophylls.
Composition of the CoreCompose of psaA and psaB subunitsCompose of D1 and D2 subunits.
The ratio of the chlorophyll carotenoid pigments20-30:1.3-7:1.

Core Difference Between Photosystem I and Photosystem II

  • Photosystem I has pigment system 1 while photosystem II has pigment system 2
  • PS1 is located on the outer surface of the thylakoid membrane while PS2 in the grana of the thylakoid membrane
  • The light wavelength of PS1 is 700nm while that of PS2 is 680nm
  • The core of PS1 contains psaA and psaB subunits while that of PS2 is D1 and D2 subunits.
  • PS1 is responsible for the synthesis of NADPH while PS2 for the synthesis of ATP and hydrolysis of water
  • PS1 does not experience photolysis of water while PS2 experience photolysis of water
  • PS2 involve in cyclic photophosphorylation whereas PS1 involved in both cyclic and non-cyclic photophosphorylation.
  • PS1 absorbs longer wavelength whereas PS2 absorb the shorter wavelength
  • PS1 result in more reducing agent whereas PS2 generate more oxidizing agent
  • PS1 has a photo center of P700 while PS2 has a photo center of P680

    • Read More: Difference between Oviparous and Viviparous Animals

    Comparison Video

    Summary

    The core difference between photosystem I and photosystem II is that photosystem I occur on the outer surface of the thylakoid membrane while photosystem II occurs in the grana of the thylakoid membrane.

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