Is PSI involved in cyclic photophosphorylation?

(Photophosphorylation = light-driven synthesis of ATP.) In some cases, electrons break this pattern and instead loop back to the first part of the electron transport chain, repeatedly cycling through PSI instead of ending up in NADPH. This is called cyclic photophosphorylation.

What is the difference between non-cyclic and cyclic photophosphorylation in relation to?

Cyclic photophosphorylation happens only in the photosystem I but non-cyclic photophosphorylation occurs in both the photosystems I and II. In the cyclic photophosphorylation, only ATP is produced, whereas, in the non-cyclic photophosphorylation both NADPH and ATP are produced.

What are the differences between linear electron flow and cyclic electron flow?

In linear electron flow (LEF), the PSs function in series and electrons are transferred all the way from water to NADP+ with concomitant production of NADPH and ATP. Cyclic electron flow (CEF), in contrast, recycles electrons around PSI by re-routing them from ferredoxin (Fd) to the plastoquinone (PQ).

What happens in PSII?

PSII is the multisubunit chloroplast membrane-associated pigment–protein complex that uses the energy of sunlight to drive the oxidation of water, evolving oxygen, donating electrons into the photosynthetic electron transfer chain, and depositing protons into the thylakoid lumen.

Where does cyclic and non-cyclic photophosphorylation occur?

Being a light reaction, non-cyclic photophosphorylation occurs in the thylakoid membrane.

Why does non-cyclic phosphorylation shift to cyclic phosphorylation?

The concentration of NADPH in the chloroplast may help regulate which pathway electrons take through the light reactions. When the chloroplast runs low on ATP for the Calvin cycle, NADPH will accumulate and the plant may shift from noncyclic to cyclic electron flow.

What are the similarities between cyclic and non-cyclic electron transport?

Similarities between cyclic and noncyclic phosphorylation Ø Both cyclic and noncyclic photophosphorylations are light reactions. Ø Both are dependent on light. Ø Both are electron transport systems. Ø Both pathways produce assimilatory powers.

What happens in noncyclic electron flow?

Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700) but not photosystem II (P680). This process produces no NADPH and no O2, but it does make ATP.

What is non-cyclic electron transport system?

Noncyclic photophosphorylation includes the flow of electron from PSII through quinone, cytochrome b6-f complex and plastocyanin to NADPH via PSI. NADP reductase enzyme is located on the stromal side of PSI and catalyzes the reduction of NADP into NADPH.

What is the function of PSII?

Photosystem II (PSII) is a multi-component pigment-protein complex that is responsible for water splitting, oxygen evolution, and plastoquinone reduction.

Does psi split water into electrons?

The photosystem II (PSII) reaction center and the photosystem I (PSI). In the photosystem II (PSII) reaction center, energy from sunlight is used to extract electrons from water. At the same time, splitting of water adds protons to the lumen, and reduction of NADPH removes protons from the stroma.

What is cyclic and non-cyclic?

Electrons passes in a cyclic manner. Electrons passes in a non – cyclic manner. Electrons return back to Photosystem I. Electrons from Photosystem I am accepted by NADP and it does not return back.

What is the difference between cyclic and non-cyclic photophosphorylation?

Let us have a look at the important differences between cyclic and non-cyclic photophosphorylation. Following are the important difference between cyclic and non-cyclic photophosphorylation: It is the synthesis of ATP coupled with electron transport activated only by PS-I.

Why is it called photophosphorylation?

Since this phosphorylation is occurring in presence of light, it is called photophosphorylation. Depending upon the path of electrons in the electron-transport-system of the primary photochemical reaction, there are two types of photophosphorylation processes. They are (1) Cyclic photophosphorylation and (2) Noncyclic photophosphorylation.

How many molecules of ATP are produced during noncyclic photophosphorylation?

Noncyclic photophosphorylation produces 1 molecule of ATP and 1 molecule of NADPH per electron pair; however carbon fixation requires 1.5 molecules of ATP per molecule of NADPH.

What is the difference between DCMU and photophosphorylation?

*Photophosphorylation: The addition of phosphate group in the presence of light during the light reaction of photosynthesis is called photophosphorylation. Photophosphorylation results in the formation of ATP during light reaction. # DCMU: It is an inhibitor of photosynthesis commonly known by the trade name Diuron.