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Update How is ATP used in photosynthesis?

Our results suggest that the ε-subunit has an essential function during ATP synthesis.

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How and Where is ATP synthesised?

One of the earliest experiments that supported the hypothesis that ATP synthesis and electron transport were linked by the electrochemical proton potential was carried out with isolated thylakoid membranes. Thylakoid membranes were placed in a buffer at pH 4.0 and after a few seconds the pH was rapidly increased to 8.0, which resulted in the formation of a proton activity gradient. This artificially formed gradient was shown to drive the synthesis of ATP from ADP and Pi. The experiments were carried out in the dark so that the possibility that electron transport contributed to the ATP synthesis was excluded. Thus, a proton activity gradient was proven capable of driving ATP synthesis.

In photosynthesis, ATP is used to drive the synthesis of the three-carbon sugar G3P.

Since two 3-phosphoglycerates are generated for each CO2 assimilated, two NADPH and two ATP are required for reduction. This reaction is the only one in photo-synthetic carbohydrate metabolism that is an oxidation-reduction reaction.

ATP is synthesized in thylakoid.

ATP is also synthesized through substrate-level phosphorylation, which is when an inorganic phosphate is added to ADP.

Glyceraldehyde 3-phosphate is a sugar phosphate and may be readily converted within chloroplasts to many sugars and the glucose polymer starch. Some of the glyc-eraldehyde 3-phosphate is used in a complex series of reactions to regenerate the five-carbon acceptor of CO2, ribulose 1,5-bisphosphate. In the process, one phosphate is cleaved from one of the sugar phosphate intermediates. Thus, ribulose 5-phosphate, the product of the cycle, must be phosphorylated by using ATP as the phosphoryl donor. As a consequence, three ATP and two NADPH are required for each CO2 taken up.

Recall that in glycolysis one of the two steps in which ATP is formed is the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate. The acylphosphate at the 1-position of the bisphosphorylated sugar acid is transferred to ADP to form ATP. The conversion of 3-phosphoglycerate to carbohydrates occurs by a pathway that is essentially the reverse of glycolysis. It must be emphasized, however, that glycolysis and photosynthetic carbon metabolism take place in separate intracellular compartments. Glycolysis occurs in the cytoplasm and uses NAD+ as the electron acceptor. The photosynthetic reduction of 3-phosphoglycerate occurs inside chloroplasts in the aqueous space known as the stroma. The enzymes in the two compartments are not the same even though they catalyze similar reactions. For example, the triose phosphate dehydrogenase in the cytoplasm is very specific for NAD+, whereas that in the chloroplast stroma is equally specific for NADPH.

how is atp synthesised in photosynthesis

The ATP synthase enzyme complex is located in the membrane, and is a remarkable rotor-stator molecular machine (Stock et al. 1999).

Importance of Photosynthesis
Photosynthesis is a process during which energy from light is harvested and used to drive synthesis of organic carbohydrates from carbon dioxide and water, generating oxygen. Photosynthesis is the only way that radiant energy from the sun can be converted into organic molecules for plants and animals to consume.

Participants in Photosynthesis
Chloroplasts are organelles specialized for photosynthesis. Inside chloroplasts are chlorophyll, proteins which can absorb light. Photosystems are many proteins together which can gather and amplify light energy. NADPH is an energy carrier in plants and ATP synthase produces the ATP.

The proton-motive force drives ATP synthesis through the action of an ATP synthase, homologous .How is ATP synthesized during photosynthesis?
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  • 18/01/2018 · ATP synthesis in mitochondria

    A single bead-enzyme complex was enclosed in a PDMS container in order to trap synthesized ATP molecules.

  • ATP formation during photosynthesis

    During photosynthesis in plants, ATP is synthesized by ATPase using a proton gradient created in the ..

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    How is ATP used in photosynthesis? - Quora

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22/01/2016 · How is ATP used in photosynthesis ..

Inspection of Eq. (5) reveals that photosynthesis is an oxidation-reduction process. Simply put, photosynthesis is the light-driven reduction of carbon dioxide to the oxidation-reduction level of a carbohydrate by using water as the electron and hydrogen donor. In the process, water is oxidized to molecular oxygen. As stated previously, water is a very poor reducing agent. However, water at an effective concentration of 55 M is readily available in the biosphere. Although organic compounds and inorganic molecules such as hydrogen sulfide are more powerful reducing agents than water is, their use in photosynthesis as the source of electrons for photosynthesis is restricted to certain species of bacteria. The thermodynamically very unfavorable reduction of carbon dioxide by water is driven by light.

ATP is synthesized during: A) cellular respiration

The general scheme for finding electrons for CO2 fixationis to open up Photosystem I and remove the electrons, eventuallygettingthem to NADP which can donate them to the dark reaction. In bacterialphotosynthesisthe process may be quite complex. The electrons are removed fromPhotosystemI at the level of a cytochrome, then moved through an energy-consumingreverseelectron transport system to an iron-sulfur protein, ferredoxin,which reduces NADP to NADPH2. The electrons that replenishPhotosystemI come from the oxidation of an external photosynthetic electrondonor,which may be H2S, other sulfur compounds, H2, orcertain organic compounds.

Basic products of photosynthesis - Encyclopedia Britannica

In plant photosynthesis, the photosynthetic electron donor is H2O,which is lysed by photosystem II, resulting in the production of O2.Electrons removed from H2O travel through Photosystem II toPhotosystem I as described in Figure 20 above. Electrons removed fromPhotosystemI reduce ferredoxin directly. Ferredoxin, in turn, passes the electronsto NADP.

The Process of Photosynthesis in Plants: An Overview

As mentioned in the previous step, most of the G3P produced during the Calvin cycle - 10 of every 12 G3P produced - are used to regenerate the RuBP so that the cycle may continue (see Fig. 1). Ten molecules of the three-carbon compound G3P eventually form six molecules of the four-carbon compound ribulose phosphate (RP) (see Fig. 1). Each molecule of RP then becomes phosphorylated by the hydrolysis of ATP to produce ribulose bisphosphate (RuBP), the starting compound for the Calvin cycle (see Fig. 1).

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