Cyclic Photophosphorylation

In cyclic electron flow, the electron begins in a pigment complex called photosystem I, passes from the primary acceptor to plastoquinone, then to cytochrome b6f (a similar complex to that found in mitochondria), and then to plastocyanin before returning to chlorophyll. This transport chain produces a proton-motive force, pumping H+ ions across the membrane; this produces a concentration gradient which can be used to power ATP synthase during chemiosmosis. This pathway is known as cyclic photophosphorylation, and it does not produce O2, as well as ATP. Unlike non-cyclic photophosphorylation, NADP+ does not accept the electrons, but they are sent back to photosystem I. NADPH is NOT produced in cyclic photophosphorylation. In bacterial photosynthesis, a single photosystem is used, and therefore is involved in cyclic photophosphorylation.

Light Dependant Reaction of Photosynthesis Animation

Light Dependent Reaction is the initial stage of Photosynthesis Where solor energy is converted into potential energy ,the light Dependent Reaction produces oxygen gas and converts ADP and NADP+ into ATP and NADPH

Process Light Dependent Reaction

Photosytem consist of rays of chlorophyll molecules, chlorophyll the green pigments of leafs absorbs light energy, and the absorbed energy excites the electrons to higher energy level. Energized electrons from photosystem 1 are passed on to electron transport chain and added to NADP+ to form NADPH, Energized electrons of photsystem 2 are passed to another electron transport chain, their energy used to pump hydrogen ions from stoma into Thylakoid compartment creating concentration gradient.

Electron leaving this electron transport chain enter photsystem 1 replenishing its lost electrons. Photosystem 2 replenished its electron by splitting water, hydrogen ions and oxygen are released in Thylakoid compartment this is were the oxygen gas generated by photosynthesis comes from, The buildup of hydrogen ions inside the thylakoid compartment stores potential energy, this energy is harvested by a enzyme called ATP synthase, as hydrogen ions diffuse through ATP synthase down the concentration gradient .the enzyme uses the energy of moving ions to make ATP, next ATP and NADPH are used in sugar making process of the Calvin cycle

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