Explain cyclic and noncyclic photo phosphorylation.
Is cyclic and noncyclic both same,if not site the differences??
Explain cyclic and noncyclic photo phosphorylation.
Is cyclic and noncyclic both same,if not site the differences??
Cyclic photophosphorylation This form of photophosphorylation occurs on the thylakoid membrane. In cyclic photophosphorylation, the high energy electron released from P700 to ps1 flow down in a cyclic pathway. 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 that can be used to power ATP synthase during chemiosmosis. This pathway is known as cyclic photophosphorylation, and it produces neither O2 nor NADPH. Unlike non-cyclic photophosphorylation, NADP+ does not accept the electrons; they are instead sent back to phytochrome b6f complex.
Non-cyclic photophosphorylation The other pathway, non-cyclic photophosphorylation, is a two-stage process involving two different chlorophyll photosystems. Being a light reaction, non-cyclic photophosphorylation occurs in the frets or stroma lamellae. First, a water molecule is broken down into 2H+ + 1/2 O2 + 2e− by a process called photolysis (or light-splitting). The two electrons from the water molecule are kept in photosystem II, while the 2H+ and 1/2O2 are left out for further use. Then a photon is absorbed by chlorophyll pigments surrounding the reaction core center of the photosystem. The light excites the electrons of each pigment, causing a chain reaction that eventually transfers energy to the core of photosystem II, exciting the two electrons that are transferred to the primary electron acceptor, pheophytin. The deficit of electrons is replenished by taking electrons from another molecule of water. The electrons transfer from pheophytin to plastoquinone, which takes the 2e− from Pheophytin, and two H+ atoms from the stroma and forms PQH2, which later is broken into PQ, the 2e− is released to Cytochrome b6f complex and the two H+ ions are released into thylakoid lumen. The electrons then pass through the Cyt b6and Cyt f. Then they are passed to plastocyanin, providing the energy for hydrogen ions (H+) to be pumped into the thylakoid space. This creates a gradient, making H+ ions flow back into the stroma of the chloroplast, providing the energy for the regeneration of ATP.
They are not the same.
cyclic photophosphorylation exists to provide energy for the calvin cycle and involves only p680 in photosystem ll and its product is ATP. Non-cyclic photophosphorylation is carried out using p700 in photosystem l and p680 in photosystem ll and it produces nadph and atp.
This form of photophosphorylation occurs on the thylakoid membrane. In cyclic photophosphorylation, the high energy electron released from P700 to ps1 flow down in a cyclic pathway. 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 that can be used to power ATP synthase during chemiosmosis. This pathway is known as cyclic photophosphorylation, and it produces neither O2 nor NADPH. Unlike non-cyclic photophosphorylation, NADP+ does not accept the electrons; they are instead sent back to phytochrome b6f complex.
Non-cyclic photophosphorylationThe other pathway, non-cyclic photophosphorylation, is a two-stage process involving two different chlorophyll photosystems. Being a light reaction, non-cyclic photophosphorylation occurs in the frets or stroma lamellae. First, a water molecule is broken down into 2H+ + 1/2 O2 + 2e− by a process called photolysis (or light-splitting). The two electrons from the water molecule are kept in photosystem II, while the 2H+ and 1/2O2 are left out for further use. Then a photon is absorbed by chlorophyll pigments surrounding the reaction core center of the photosystem. The light excites the electrons of each pigment, causing a chain reaction that eventually transfers energy to the core of photosystem II, exciting the two electrons that are transferred to the primary electron acceptor, pheophytin. The deficit of electrons is replenished by taking electrons from another molecule of water. The electrons transfer from pheophytin to plastoquinone, which takes the 2e− from Pheophytin, and two H+ atoms from the stroma and forms PQH2, which later is broken into PQ, the 2e− is released to Cytochrome b6f complex and the two H+ ions are released into thylakoid lumen. The electrons then pass through the Cyt b6and Cyt f. Then they are passed to plastocyanin, providing the energy for hydrogen ions (H+) to be pumped into the thylakoid space. This creates a gradient, making H+ ions flow back into the stroma of the chloroplast, providing the energy for the regeneration of ATP.
They are not the same.
cyclic photophosphorylation exists to provide energy for the calvin cycle and involves only p680 in photosystem ll and its product is ATP. Non-cyclic photophosphorylation is carried out using p700 in photosystem l and p680 in photosystem ll and it produces nadph and atp.
