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Home > Articles > Differentiate Between Cyclic and Noncyclic Photophosphorylation: Definitions, Similarities and Key Differences
Updated on 02nd May, 2023 , 4 min read
Photosynthesis is the process through which light energy is converted into chemical energy. The acquired solar energy is used to convert carbon dioxide and water into glucose and oxygen. The photosynthetic process is divided into two parts: the light reaction and the dark reaction. Photophosphorylation is the insertion of a phosphate group during the light reaction of photosynthesis in the presence of light.
Otto Kandler discovered photophosphorylation in vivo for the first time in 1950, using whole Chlorella cells, and interpreted his findings as light-dependent ATP generation. In 1954, Daniel I. Arnon used P32 to identify photophosphorylation in isolated chloroplasts in vitro. He published his first overview of early photophosphorylation experiments in 1956. Photophosphorylation is the conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) using light energy from photosynthesis (ATP). It is the mechanism by which energy-rich ATP molecules are generated in the presence of sunlight by transferring the phosphate group to the ADP molecule.
Photophosphorylation is of 2 Different Types, which are as follows-
The following table gives definitions related to the difference between cyclic and noncyclic photophosphorylation-
Cyclic Photophosphorylation |
Noncyclic Photophosphorylation |
Cyclic Photophosphorylation is the mechanism by which ADP is converted into ATP to create energy for the cells' immediate needs. |
Noncyclic photophosphorylation is a mechanism that harnesses the energy from excited electrons created by Photosystem II to cause non-cyclic electron movement, which results in the formation of ATP molecules. |
In cyclic photophosphorylation, only one photosystem (PS I) is employed, and there is no reduction in NADP+. |
The protons (H+) are formed when water molecules split and interact with electrons to reduce NADP to NADPH. The following equation depicts the reaction. NADPᐩ+ 2Hᐩ+ 2e⁻→ NADPH + Hᐩ |
The following table gives the difference between cyclic and noncyclic photophosphorylation-
Parameters |
Cyclic Photophosphorylation |
Noncyclic Photophosphorylation |
Meaning |
The process of producing ATP during the cyclic electron transport chain of light-dependent photosynthesis is referred to as "cyclic photophosphorylation." |
Noncyclic photophosphorylation is the method by which ATP is produced from the noncyclic electron transport chain in photosynthetic light reactions. |
Photosynthesis Found |
Anaerobic condition |
Aerobic condition |
Photosystem |
PS-I |
PS-II |
Product |
ATP |
Reduced coenzymes and ATP |
Oxygen Production |
Yes |
No |
Occurrence |
Photosynthetic bacteria and isolated chloroplast |
Algae, cyanobacteria, plants, etc. |
Electron Acceptor |
P700 |
NADP+ |
Flow Pattern of Electrons |
Cyclic |
Linear |
Electron donor |
P700 |
P680 |
Photolysis of water |
Water does not split during this process |
Water splits or photolyzes |
Carbon dioxide involvement |
Occurs when the CO2 concentration is less in the atmosphere |
Occurs at normal CO2 concentration |
Effect of Diuron |
The process is not inhibited by diuron |
The process is sensitive to the diuron |
The following are some of the similarities between cyclic and noncyclic photophosphorylation-
The following are the distinctions between cyclic and noncyclic photophosphorylation-
Sample Question 1: Define the term "photophosphorylation."
Photophosphorylation is the insertion of a phosphate group during the light reaction of photosynthesis in the presence of light. Photophosphorylation is phosphorylation that takes place in the presence of light.
Sample Question 2: What are the two different forms of photophosphorylation?
Ans: Photophosphorylation is classified into two types: cyclic photophosphorylation and non-cyclic photophosphorylation.
Sample Question 3: Describe the non-cyclic photophosphorylation mechanism.
When electrons are liberated from the excited photo center and do not return, the process of non-cyclic photophosphorylation occurs. Only when both photosystems I and II are involved does this process occur. Water photolysis results in the release of electrons. As a result, a consistent supply of water is necessary for this operation. During this process, both NADPH and ATP are produced.
Sample Question 4: Which of the following scenarios is optimal for cyclic photophosphorylation?
The cyclic photophosphorylation approach is only suitable for bacteria.
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By - Nikita Parmar 2024-09-06 10:59:22 , 6 min readAns. Proton Motive Force is the other main source of energy in photophosphorylation.
Ans. Cyclic photosynthesis generates ATP but not NADPH.
Ans. Phosphorylation is the mechanism by which ATP is produced from ADP during the light response of photosynthesis. This process can be carried out in two ways: cyclic photophosphorylation and non-cyclic photophosphorylation. The process in which electrons are released from the exciting photo center and do not return is referred to as non-cyclic photophosphorylation. When both photosystems I and II are involved, this process occurs. Because the photolysis of water results in the release of electrons, a steady supply of water is required. Both NADPH and ATP are generated during this process.
Ans. Cyclic flow of pattern in the cyclic and linear flow of pattern in noncyclic photophosphorylation.
Ans. The following equation depicts the reaction: NADPᐩ+ 2Hᐩ+ 2e⁻→ NADPH + Hᐩ