Which term describes ATP production resulting from the capture of light energy by chlorophyll?

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Which term describes ATP production resulting from the capture of light energy by chlorophyll?

In the process of Photosynthesis, which term can describe ATP production resulting from the capture of light energy by chlorophyll?

1. Oxidative phosphorylation
2. Substrate-level phosphorylation
3. De-phosphorylation
4. Photophosphorylation

Photosynthesis

Photosynthesis is a biochemical process in which chloroplast-containing green plants and certain bacteria, under the irradiation of visible light, undergo a photoreaction and a carbon reaction, using photosynthetic pigments to convert carbon dioxide and water into organic matter and to release oxygen.

The process of photosynthesis also involves the energy conversion of light energy into chemical energy in organic matter.

Photophosphorylation

Photophosphorylation is a reaction in which the cystoid membrane of plant chloroplasts or the chromophore of photosynthetic bacteria catalyzes the formation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and phosphate (Pi) in the presence of light.

There are two types of Photophosphorylation: cyclic and non-cyclic photosynthetic phosphorylation.

The former is phosphorylation that occurs simultaneously during the cyclic electron transfer of the photoreaction, producing ATP.

In the latter, phosphorylation occurs simultaneously during the non-cyclic electron transfer of the light reaction, producing ATP. In the non-cyclic electron transfer pathway, electrons ultimately come from water and finally pass to oxidative coenzyme II (NADP+). Thus, along with the formation of ATP, oxygen is released and reduced coenzyme II (NADPH) is formed.

In the light reaction of photosynthesis, in addition to transferring part of the light energy to NADPH for temporary storage, another part of the light energy is used to synthesize ATP, coupling photosynthesis with the phosphorylation of ADP, a process called photosynthetic phosphorylation.

The main difference between this process and oxidative phosphorylation in mitochondria is that oxidative phosphorylation is driven by the oxidation of high-energy compound molecules, whereas photosynthetic phosphorylation is driven by photons.

The mechanism of photosynthetic phosphorylation is similar to that of oxidative phosphorylation carried out by mitochondria. Again, this can be explained by the doctrine of chemiosmosis. The coupling between electron transport and ATP synthesis is the proton electrochemical gradient between the inner and outer membrane.

Chloroplast ATPase

The enzyme that catalyzes the synthesis of ATP in chloroplasts is very similar to the ATPase in mitochondria. Chloroplast ATPases are also located on the outside of the vesicle-like membrane like a door handle. It is present in the unstacked vesicle-like membrane.

ATPase can be divided into two parts, CF1 and CF0. CF0 is inserted into the membrane and acts as a proton channel. CF1 consists of α3, β3, γ, δ and ε subunits. α and β subunits have the function of binding ADP, γ subunit controls proton flow, δ subunit binds to CF0, and ε subunit has the function of inhibiting catalysis in the dark, restricting ATP hydrolysis and avoiding wasteful behavior.

CF1 is on the substrate side, so the newly synthesized ATP is released into the substrate. CF0 is composed of at least three subunits, and oligomycin can inhibit the ATPase activity and thus can block the photosynthetic phosphorylation.

The formula of photosynthesis：

6CO₂ + 6H₂O ——→ C₆H₁₂O₆ + 6O₂

Oxidative phosphorylation

Oxidative phosphorylation refers to the role in biological oxidation accompanied by ATP production. There are two types of metabolite-linked phosphorylation and respiratory chain-linked phosphorylation. There are two ways of ATP generation.

One type is the redistribution of energy within the molecule after metabolite dehydrogenation so that inorganic phosphorylation first forms a high-energy intermediate metabolite that drives ADP to ATP. this is called substrate-level phosphorylation.

For example, 3-phosphoglyceraldehyde is oxidized to form 1,3-diphosphoglyceric acid, which is then degraded to 3-phosphoglyceric acid.

The other is the generation of coupled ATP during electron transport in the respiratory chain. Ninety-five percent of the ATP in an organism comes from this way.

The difference between oxidative phosphorylation and substrate horizontal phosphorylation:

Substrate horizontal phosphorylation is the redistribution of energy within a metabolic substrate as a result of dehydrogenation or dehydration of its molecule. The energy carried by the resulting high-energy bonds is transferred to ADP to generate ATP, i.e. the formation of ATP is directly coupled to the transfer of a phosphate group on a metabolically intermediate high-energy phosphate compound.

Substrate horizontal phosphorylation is characterized by the fact that it does not require the participation of molecular oxygen.

Uncoupling of oxidative phosphorylation

In intact mitochondria, electron transfer and phosphorylation are tightly coupled. When the two processes, electron transfer, and ATP formation, are separated by the use of certain reagents, and only electron transfer but not ATP formation takes place, the effect is called uncoupling.

The reagents that cause uncoupling are called uncoupling agents. The essence of uncoupling is that the uncoupling agent eliminates the concentration or potential gradient of transmembrane protons generated in electron transfer, and only electron transfer without ATP is produced.

Oxidative phosphorylation coupling During biological oxidation, when hydrogen shed by metabolites is oxidized by the respiratory chain to produce water, the energy released is used for ADP phosphorylation to produce ATP.

The sites of ATP formation in the electron transport chain are different.

Substrate-level phosphorylation

Substrate horizontal phosphorylation refers to the exergonic hydrolysis of high-energy compounds or ATP synthesis coupled to group transfer.

The substrate level phosphorylation does not include photosynthetic phosphorylation or oxidative phosphorylation in the respiratory chain for ATP generation processes.

Correct Answer

Here is the answer to Which term describes ATP production resulting from the capture of light energy by chlorophyll?

In the process of Photosynthesis, Photophosphorylation can describe ATP production resulting from the capture of light energy by chlorophyll.

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