Cyclic vs Non-Cyclic Photophosphorylation: Difference and Comparison

It is the mechanism through which energy-enriched adenosine triphosphate molecules are produced in the presence of light by transferring the phosphate group to the adenosine diphosphate molecule. 

Since phosphorylation happens in the visible region of light, it is referred to as photophosphorylation.

Key Takeaways

  1. Cyclic photophosphorylation generates ATP without producing NADPH, while non-cyclic photophosphorylation generates both ATP and NADPH.
  2. Cyclic photophosphorylation involves only Photosystem I, whereas non-cyclic photophosphorylation uses both Photosystem I and Photosystem II.
  3. Cyclic photophosphorylation does not consume water or release oxygen, but non-cyclic photophosphorylation splits water molecules, releasing oxygen as a byproduct.

Cyclic Photophosphorylation vs Non-Cyclic Photophosphorylation

The difference between cyclic photophosphorylation and non-cyclic photophosphorylation is that cyclic photophosphorylation develops through anoxygenic photosynthesis, whereas non-cyclic photophosphorylation takes place during oxygenic photosynthesis.

Cyclic Photophosphorylation vs Non Cyclic Photophosphorylation
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Plant cells make adenosine diphosphate to adenosine triphosphate during this process to achieve instant energy for the cells. Cyclic photophosphorylation is a mechanism that happens in the thylakoid membrane and utilizes Chlorophyll P700 and Photosystem I.

Because the electrons emitted via P680 of Photosystem II are taken with P700 of Photosystem I and therefore do not return to P680, this mechanism is known as non-cyclic photophosphorylation.

Comparison Table

Parameters of ComparisonCyclic PhotophosphorylationNon-Cyclic Photophosphorylation  
PresenceThis is most common among photosynthetic bacteria.It is found mostly in higher plants, algae, and cyanobacteria.
Electron flow patternElectrons flow in a cyclic or circular manner.Electrons flow in a zig-zag pattern in a uniform manner.
Release of oxygenDuring cyclic photophosphorylation, no oxygen is produced.Non-cyclic photophosphorylation produces molecular oxygen.
Involvement of photosystemOnly photosystem-I is involved.It is made up of photosystems I and II.
Creation of energyIn this procedure, just adenosine triphosphate is generated.This process generates adenosine triphosphate and NADPH.

What is Cyclic Photophosphorylation?

Cyclic Photophosphorylation is the mechanism by which organisms (such as prokaryotes) convert adenosine diphosphate to adenosine triphosphate for quick energy.

It then moves from the main acceptor to ferredoxin and subsequently to cytochrome b6f. Cytochrome b6f is comparable to mitochondrial cytochrome b6f.

A proton-motive force is created throughout the electron acceptor chain, which pumps H+ ions out of the cell and creates a pressure gradient that may be utilized to activate adenosine triphosphate synthase during chemiosmosis.

Even during cyclic photophosphorylation reaction, electrons are transported back to P700 from the acceptor and therefore do not travel to NADP.

Cyclic photophosphorylation is always necessary since it produces adenosine triphosphate at a cheap cost. In cyclic photophosphorylation, only photosystem-I is engaged.

What is Non-Cyclic Photophosphorylation?

Non-cyclic photophosphorylation is a two-step process that involves two distinct chlorophyll photons. Non-cyclic photophosphorylation happens in the thylakoid membrane as a light response.

Non-cyclic photophosphorylation is prevalent in all vegetation, algae, and cyanobacteria. PS-II absorbs photons from the source of light and transmits them to RC chlorophyll.

The electrons interact with both the protons H+ generated when the water particles break to decrease NADP into NADPH.

This is the only way electrons transfer from a molecule of water to NADPH. As a result, it is known as non-cyclic photophosphorylation.

Glycerate 3-phosphate is the fundamental building block from which plants may produce a wide range of compounds. Non-cyclic photosynthetic respiration produces molecular oxygen in the contribution of energy molecules.

Main Differences Between Cyclic Photophosphorylation And Non-Cyclic Photophosphorylation

  1. Cyclic photophosphorylation requires ATP synthesis, but non-cyclic photophosphorylation requires ATP synthesis as well as the generation of NADPH.
  2. Cyclic photophosphorylation involves just photosynthesis, whereas non-cyclic photophosphorylation involves both photosynthesis I and II.
References
  1. https://www.sciencedirect.com/science/article/pii/0005272872901430
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC223143/

Last Updated : 11 June, 2023

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