The process of attachment of phosphate group in the presence of light during the light reaction of photosynthesis is known as photophosphorylation.
In cyclic photophosphorylation the electrons move in a cyclic manner and in non cyclic photophosphorylation the electrons don't move in a cyclic manner...
Few other differences are:In cyclic only PS1 is involved whereas in non cyclic both PS l and PS ll are required. In cyclic water is not required in non cyclic photolysis of water is required. In cyclic oxygen is not evolved in non cyclic oxygen is evolved.NADPH is not synthesised but in non cyclic NADPH is synthesised...

Difference between Cyclic and Noncyclic Photophosphorylation

Photophosphorylation is the process in which light energy is used to generate ATP (adenosine triphosphate) in plants and some bacteria during photosynthesis. There are two types of photophosphorylation: cyclic and noncyclic. Let's discuss the differences between these two processes.

Cyclic Photophosphorylation:
Cyclic photophosphorylation is a type of photophosphorylation that occurs only in the photosystem I (PS I) of the chloroplasts. Here, the excited electrons from chlorophyll molecules are passed through a series of electron carriers, ultimately returning to the same chlorophyll molecule from where they originated. This process does not involve the splitting of water and the release of oxygen. The key points of cyclic photophosphorylation are:

1. Electron Flow: The excited electrons from PS I are transferred to a primary electron acceptor and then passed through a series of electron carriers, including ferredoxin and cytochrome complex back to the chlorophyll molecule.

2. ATP Production: During the electron flow, the energy released is used to pump protons across the thylakoid membrane, creating a proton gradient. This gradient is then used by ATP synthase to generate ATP.

3. NADPH Production: Unlike noncyclic photophosphorylation, cyclic photophosphorylation does not produce NADPH as there is no electron flow to photosystem II (PS II).

Noncyclic Photophosphorylation:
Noncyclic photophosphorylation occurs in both photosystem I (PS I) and photosystem II (PS II) of the chloroplasts. It involves the transfer of excited electrons from PS II to PS I and ultimately to NADP+ (nicotinamide adenine dinucleotide phosphate) to produce NADPH. The key points of noncyclic photophosphorylation are:

1. Electron Flow: The excited electrons from PS II are transferred to a primary electron acceptor and then passed through a series of electron carriers, including plastoquinone and cytochrome complex, before reaching PS I. From PS I, the electrons are transferred to a second electron acceptor and ultimately to NADP+ to form NADPH.

2. ATP Production: As the electrons flow through the electron transport chain, energy is released, which is used to pump protons across the thylakoid membrane, creating a proton gradient. ATP synthase then utilizes this gradient to produce ATP through chemiosmosis.

3. Water Splitting: Noncyclic photophosphorylation involves the splitting of water molecules in PS II. This process releases oxygen as a byproduct.

4. NADPH Production: In noncyclic photophosphorylation, the transfer of electrons from PS I to NADP+ leads to the production of NADPH. This molecule is essential for the Calvin cycle, where it acts as a reducing agent.

Overall, the main difference between cyclic and noncyclic photophosphorylation lies in the electron flow and the production of NADPH. Cyclic photophosphorylation only involves PS I and generates ATP, while noncyclic photophosphorylation involves both PS I and PS II, produces ATP and NADPH, and