Where Do the Electrons Needed by Photosystem II Originate?

where do the electrons needed by photosystem ii originate

Where do the electrons needed by photosystem li and ii come from? These two components of photosynthesis are vital for energy production in plants. In order for them to function, they must absorb incoming light and transfer them to the electron transport chain. The electrons in a cyclic electron flow begin in the pigment complex called photosystem I. They then pass from their primary acceptor to ferredoxin, plastoquinone, cytochrome b6f, plastocyanin, and subsequently back to Photosystem I.

The transport chain is a series of membrane carriers. Electrons move from one atom to another in a series of steps to create water and ATP. The electrons are then coupled to the synthesis of a second molecule called NADPH. This process is the most efficient way of producing energy in plants. Electrons are generated by cosmic rays, radioactive isotopes, and high-energy collisions.

The higher plants have two photosystems. One is responsible for absorbing light, while the other is responsible for capturing energy from the sun. The energy in sunlight is used to elevate electrons, which then move downhill to the NADPH compound. This process involves two phases, light and dark. Light cycle is a period of growth and reproduction while the dark cycle occurs when plants capture CO2 from the atmosphere.

In contrast, dark reactions are not required for light reactions. Light reactions in photosystem ii capture energy from the sunlight and convert it to chemical energy, which is then stored in NADPH and ATP. The light reaction also produces oxygen gas as waste. These two components work together to produce sugars, the ultimate energy storage directly arising from photosynthesis. You might be asking yourself – where do the electrons need to come from?

In addition to energy production, electrons from photosystems I and ii are used by the Calvin cycle enzymes in the chloroplast stroma to create ATP and NADPH. These compounds are then used by the Calvin cycle, an enzyme in the plant’s metabolism to convert CO2 into carbohydrates. The energy they supply for photosynthesis is vital to the survival of the plant.

The cyanobacterial PSII crystal structure was recently determined and shows an alternative electron movement path, where the electrons can travel backward through the b6f complex and ferredoxin. The cyclic route produces more ATP, and is similar to the path taken by green sulfur bacteria. In addition, plants can switch between non-cyclic and cyclic photosystems, generating a proper ratio of ATP and NADPH. The correct ratio between the two is 3 ATP to two NADPH.

When sunlight hits a plant’s leaf, the chloroplast absorbs the energy by splitting water. The energy in the sunlight splits water molecules, releasing two electrons, two hydrogen atoms, and one oxygen atom. The resulting monomer of chlorophyll a molecule achieves an energy level that is unstable, so the electrons flow between photosystems lose energy in the process.

As a result, the membrane that surrounds the PSII structure must be able to provide insulation for the protein components. It also needs to be stable in its reduced state. Its components must be able to self-assemble in their unique surroundings, which is achieved through protein-protein and protein-lipid interactions. Furthermore, complementary protein surfaces add rigidity to the cofactors while the lipid bilayer imparts flexibility to the dynamic movements.

ATP is a necessary component of the reactions in which the sunlight is converted into chemical energy. ATP synthase is a multiprotein complex that consists of antenna proteins and 300 to 400 chlorophyll a and b molecules. The reactions in these systems take place in the chloroplast thylakoid membrane. Photosystem II transfers electrons via coenzymes. It then reduces plastoquinone to plastoquinol, which is then oxidized by water and forms molecular oxygen and hydrogen ions.

The electrons required by photosystem II originate in two ways. The first is transported to the cytochrome bf complex, where the proton gradient drives ATP synthesis. The second is transferred to the plastocyanin, which holds the electron until the next excitation process. The final process is a noncyclic electron flow, which gives one to 1.5 ATP molecule per pair of electrons.

The other way PSII obtains electrons is through photodamage. Photodamage results in the crosslinking of the D1 protein. This crosslinking inhibits the degradation process. Consequently, the electrons needed for photosystem ii degrade and accumulate in the cytoplasm. This is the mechanism that protects plants from damage by sunlight. The second mechanism involves a novel ET conduit, which can facilitate photoautotrophic growth in plants.