What is a non-periodic electron flow? This cooperative process of energy production is called acyclic photophosphorylation and the transfer of electrons from water to NADPH, known as the mound reaction, is acyclic electron flow. Light is absorbed in PS II, causing the photosystem to strip electrons from the water and excite them to a primary acceptor.
What is periodic electron flow? In the periodic electronic flow (CEF), electrons are recycled around the first photosystem. As a result, a transthylakoid proton gradient (ΔpH) is generated, which leads to the production of ATP without the concomitant production of NADPH, thus increasing the ratio of ATP/NADPH within the chloroplast.
Why is electron flow called acyclic? As the electron moves down the chain, the excessive energy “drop” is harnessed to a lower energy level by the thylakoid membrane to produce ATP (by chemosmosis). This process of ATP production is called acyclic photophosphorylation.
What is the purpose of a non-periodic electron flow? Non-cyclic electron transfer is the most important in photosynthesis as it provides assimilation power in the form of NADPH and ATP to assimilate carbon dioxide and purifies atmospheric air. Accepting electrons instead are sent back to the cytochrome b6f complex.
What is a non-periodic electron flow? Related Questions
What results from a non-periodic electron flow?
In non-cyclic photophosphorylation both NADPH and ATP are produced while in single cycle only ATP is produced. When the plant has sufficient reducing factor (NADPH), there is no need to produce more NADPH which includes both photosystems (I and II). In cyclic photophosphorylation, only the photosynthetic system is active.
What is the function of periodic electron flow?
In higher plants, generation of a proton gradient across the thylakoid membrane (ΔpH) through cyclic electron flow (CEF) has two primary functions: (1) to generate ATP and balance the ATP/NADPH energy budget, and (2) to protect photosystems I and II against photosynthesis.
What is the main function of cyclic photophosphorylation?
The process of photophosphorylation that leads to the cyclic movement of electrons to synthesize ATP molecules is called cyclic photophosphorylation. In this process, plant cells convert ADP into ATP for instant energy for the cells.
What is the difference between linear and periodic electronic flow?
In a linear electron flow (unbroken arrows), energy from the absorbed photons is used to oxidize the water on the bright face of Photosystem II (PS II). In a periodic electron flow, energy from the absorbed photons causes the oxidation of the reaction center (P700) in PS I.
What is the difference between periodic and non-periodic electronic flow?
In periodic photophosphorylation, the electrons are expelled by the first photosystem and return to the system. On the other hand, in non-cyclic photophosphorylation, the electrons that are ejected by the photosystems do not return.
What happens in acyclic photophosphorylation?
In a process called acyclic photophosphorylation (the “standard” form of light-dependent reactions), electrons are removed from the water and passed through PSII and PSI before ending up in NADPH. This process requires the light to be absorbed twice, once in each photosystem, and to make ATP.
Does cyclic photophosphorylation occur at low light intensities?
It occurs in the case of low light intensities and light of wavelength less than 680 nm and when carbon dioxide fixation is inhibited. Plants are able to produce energy by using photons from sunlight through photophosphorylation.
Where does acyclic photophosphorylation occur?
Full answer: Acyclic phosphorylation occurs in the granular thylakoid region of the chloroplast. Two photosystems, i.e. photosystem I and photosystem II, are involved in the acyclic phosphorylation process.
What does non-periodic mean?
: not related to cycles or occurring in cycles: not a cyclical process a non cyclical industry a non cyclical industry.
What is meant by acyclic photophosphorylation?
Non-cyclic photophosphorylation: The light-requiring part of photosynthesis in higher plants, which requires an electron donor, and oxygen is produced as a waste product. It consists of two photoreactions, which leads to the synthesis of ATP and NADPH 2.
Why is the cyclic path important?
By using the cyclic pathway, plants can save some time and energy. Since the first photosystem accepts electrons that are returned to it, it does not accept electrons from the previous electron transport chain. Therefore, the first electron transport chain will be backed up, which means that photolysis will not occur.
Is periodic electronic flow important in this process?
The interactions involve two types of electron flow in the thylakoid membrane. The role of cyclic electron transfer around PS I is suggested to be necessary to balance the ratio of ATP/NADPH production and/or to protect both photosystems from damage by excessive stromal reduction.
Where does PhotoSystem 2 get its electrons?
The second photosystem gets alternate electrons from water molecules, causing them to split into hydrogen ions (H +) and oxygen atoms. The oxygen atoms combine to form molecular oxygen (O2), which is released into the atmosphere.
What do you mean by periodic photophosphorylation?
Cyclic photophosphorylation can be defined as ATP synthesis coupled with electron transfer that is activated by photosystem I only and thus can proceed in long-wave light (03BB 2265700 nm). This process is not affected by specific inhibitors of Photosystem II, such as CMU, DCMU and orthophenanthroline.
Is oxygen produced in cyclic photophosphorylation?
Photophosphorylation occurs on the lamellar stroma or fret. In cyclic photophosphorylation, the high-energy electron free from p700 to ps1 flows into a cyclic pathway. This pathway is identified as cyclic photophosphorylation, producing neither oxygen (O2) nor NADPH.
Which of the following is correct for cyclic photophosphorylation?
The net yield of cyclic photophosphorylation is ATP. The correct answer is b.
Why is neither oxygen nor NADPH generated by cyclic electronic flow?
Why is neither oxygen nor NADPH generated by cyclic electron flow? Electrons do not move from P680 to P700 and without it, water does not dissociate, which means that NADPH cannot form from NADP+.
Does water separate in acyclic photophosphorylation?
There is no water splitting – the electrons come from the light harvesting complex only. When the electrons reach the end of the chain, they go back to the beginning of the chain rather than helping to form NADPH as there is no NADP to accept it.
How are electrons replaced in non-cyclic photophosphorylation?
During the non-cyclic photophosphorylation process, the generation of ATP is coupled with a unidirectional flow of electrons from H2O to NADP+. These electrons replace the electrons lost by chlorophyll molecules P680 in the reaction centers of the photosystem II antenna complexes (Fig. 18.7B.2).
Which of the following is exclusively present in acyclic photophosphorylation?
Stroma lamellae lack PS II as well as the enzyme NADP reductase while Grana lamellae contain both PS I and PS II. Thus, the correct answer is option (b).
Why is the dark reaction called that?
It occurs more quickly at night. Reactions do not require light. Instead, the assimilative energy (ATP and NADPH) produced during the photochemical phase is used to fix and reduce carbon dioxide.
