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In cyclic photophosphorylation, the high-energy electron released from P700, a pigment in a complex called photosystem I, flows in a cyclic pathway. The electron starts in photosystem I, passes from the primary electron acceptor to ferredoxin and then to plastoquinone , next to cytochrome b 6 f (a similar complex to that found in mitochondria ...
In cyclic photophosphorylation, cytochrome b 6 f uses electrons and energy from PSI to create more ATP and to stop the production of NADPH. Cyclic phosphorylation is important to create ATP and maintain NADPH in the right proportion for the light-independent reactions. The net-reaction of all light-dependent reactions in oxygenic photosynthesis ...
If electrons only pass through once, the process is termed noncyclic photophosphorylation, but if they pass through PSI and the proton pump multiple times it is called cyclic photophosphorylation. When the electron reaches photosystem I, it fills the electron deficit of light-excited reaction-center chlorophyll P700 + of PSI.
Photosystem I operates with the functions of producing NADPH, the reduced form of NADP + (Fd 2-red + NADH + 2 NADP + + H + = Fd ox + NAD + + 2 NADPH.), at the end of the photosynthetic reaction through electron transfer, and of providing energy to a proton pump and eventually ATP, for instance in cyclic electron transport.
Cyclic electron transport or cyclic photophosphorylation produces only ATP. The noncyclic variety involves the participation of both photosystems, while the cyclic electron flow is dependent on only photosystem I. Photosystem I uses light energy to reduce NADP + to NADPH + H +, and is active in both noncyclic and cyclic electron transport. In ...
In non-cyclic photophosphorylation, ferredoxin is the last electron acceptor thus reducing the enzyme NADP + reductase. It accepts electrons produced from sunlight - excited chlorophyll and transfers them to the enzyme ferredoxin: NADP + oxidoreductase EC 1.18.1.2 .
to NADPH or are used in non-cyclic electron flow. [1] DCMU is a chemical often used in laboratory settings to inhibit photosynthesis. When present, DCMU inhibits electron flow from photosystem II to plastoquinone.
Plastoquinone (PQ) is a terpenoid-quinone (meroterpenoid) molecule involved in the electron transport chain in the light-dependent reactions of photosynthesis.The most common form of plastoquinone, known as PQ-A or PQ-9, is a 2,3-dimethyl-1,4-benzoquinone molecule with a side chain of nine isoprenyl units.