What is the difference between the roles of photosystems i and ii

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. Photosystem I includes the following pigments: Chlorophyll b, Chlorophyll -a , Chlorophyll -a , Chlorophyll -a , Chlorophyll -a or P, Carotenoids. In photosystem I, P form of chlorophyll a is the active reaction centre. In photosystem II, P form of chlorophyll a is the active reaction centre. Photosystem I PS I. PS I is located at the outer surface of the grana thylakoid membrane non appressed granal regions and stroma lamella.

PS II is located at the inner surface of the grana thylakoid membrane appressed granal region. The photocentre or reaction centre is P The photocentre is P Rich in chlorophyll a than chlorophyll-b.

Rich in chlorophyll b than chlorophyll-a. 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. Location It is located on the outer surface of the thylakoid membrane. It is located on the inner surface of the thylakoid membrane. Photocenter or reaction centre P is the photo center. P is the photo center. Absorbing wavelength The pigments in the photosystem 1 absorb longer wavelengths of light which is nm P The pigments in the photosystem2 absorb shorter wavelengths of light which is nm P Photophosphorylation This system is involved in both cyclic as well as non-cyclic photophosphorylation.

This system is involved in both cyclic photophosphorylation. Photolysis No photolysis occur. Photolysis occurs in this system. The ratio of the chlorophyll carotenoid pigments Photosystem I or PSI is located in the thylakoid membrane and is a multisubunit protein complex found in green plants and algae. The first initial step of trapping solar energy and the then conversion by light-driven electron transport.

PS I is the system where the chlorophyll and other pigments get collected and absorb the wavelength of light at nm. It is the series of reaction, and the reaction center is made up of chlorophyll a, with the two subunits namely psaA and psaB. This system also consists of the chlorophyll a, chlorophyll a, chlorophyll a, chlorophyll b, and carotenoids. The absorbed photons are carried into the reaction center with the help of the accessory pigments.

Figure 1: A photosystem 1 — Sunlight, 2 — Pigments, 3 — Reaction center, 4 — high energy electron flow, 5 — photosystem. PS II is the collection of pigments of chlorophyll, absorbing mostly the wavelength of light at nm. The first stage of the light reaction is catalyzed by PS II. PS II consists of a lot of other proteins and pigments arranged in the photosystem.

The pigments are chlorophyll A, chlorophyll A, chlorophyll A, chlorophyll A, chlorophyll A, chlorophyll B and phycobilins and xanthophylls. PS II achieves energy from absorbing photons or associated accessory pigments in the antenna complex.

High energy electrons are generated from the energy of the absorbed photons. These electrons are passed through an electron transport chain.

During the electron transport chain, PS II passes electrons to plastoquinone PQ , which carries the electrons to cytochrome bf complex. For each water molecule, that is hydrolyzed, two molecules of PQH2 are formed. The overall reaction in PS II is shown below. Photosystem 1: Photosystem 1 is located on the outer surface of the thylakoid membrane.

Photosystem 2: Photosystem 2 is located on the inner surface of the thylakoid membrane. Photosystem 1: The photocenter of the photosystem 1 is P Photosystem 2: The photocenter of the photosystem 2 is P Photosystem 1: Photosystem 1 is involved in both cyclic and non-cyclic photophosphorylation.