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Where does the energy to excite the electrons in photosystem I come from?
Photosystem I is really the second photosystem. When light photons excite the pigments in the light-harvesting complexes of the photosystem, their electrons get excited. These electrons come from the process the directly proceeds Photosystem I, which is the electron transport chain.
What does photosystem I produce with energized electrons?
In cyclic photophosphorylation, the energized electron released by the photosystem and used in the electron transport chain is returned to photosystem I. This process produces ATP.
How do electrons gain energy in the photosystem 1?
From photosystem II, electrons are carried by plastocyanin (a peripheral membrane protein) to photosystem I, where the absorption of additional photons again generates high-energy electrons. Photosystem I, however, does not act as a proton pump; instead, it uses these high-energy electrons to reduce NADP+ to NADPH.
What happens in the photosystem 1?
Photosystem I receives electrons from plastocyanin or cytochrome c6 on the lumenal side of the thylakoid membrane and uses light energy to transfer them across the membrane to ferredoxin on the stromal side. It can also function in a cyclic electron transport pathway.
Where do the excited electrons come from in photosystem II?
The light excites an electron from the chlorophyll a pair, which passes to the primary electron acceptor. The excited electron must then be replaced. In (a) photosystem II, the electron comes from the splitting of water, which releases oxygen as a waste product.
What enables electrons to excited?
When an electron temporarily occupies an energy state greater than its ground state, it is in an excited state. An electron can become excited if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby atom or particle.
What does each photosystem produce?
Each photosystem consists of multiple antenna proteins that contain a mixture of 300–400 chlorophyll a and b molecules, as well as other pigments like carotenoids. Cytochrome b6f complex and ATP synthase are also major protein complexes in the thylakoid membrane that work with the photosystems to create ATP and NADPH.
How do electrons gain energy in photosystem 2?
The heart of photosystem II is the reaction center, where the energy of light is converted into the motion of energized electrons. At the center is a key chlorophyll molecule. When it absorbs light, one of its electrons is promoted to a higher energy.
What happens to the electrons after photosystem 1?
The electron arrives at photosystem I and joins the P700 special pair of chlorophylls in the reaction center. When light energy is absorbed by pigments and passed inward to the reaction center, the electron in P700 is boosted to a very high energy level and transferred to an acceptor molecule.
What is the source of energy that excites the electron in photosystem II?
In the photosystem II (PSII) reaction center, energy from sunlight is used to extract electrons from water. The electrons travel through the chloroplast electron transport chain to photosystem I (PSI), which reduces NADP+ to NADPH. The electron transport chain moves protons across the thylakoid membrane into the lumen.
How are the excited electrons replaced in photosystem I?
To replace the electron in the reaction center, a molecule of water is split. This splitting releases an electron and results in the formation of oxygen (O2) and hydrogen ions (H+) in the thylakoid space.
What happens when electrons get excited in photosystem I?
NADP+ (NADPH) is the result of the electrons which combine to produce an energy carrying molecule. This happens when the electrons get excited in photosystem I. Took the quiz!
What do electrons combine to produce an energy-carrying molecule?
Electrons are excited in photosystem I. With what do these electrons combine to produce an energy-carrying molecule? A.ADP NADP+ (NADPH) is the result of the electrons which combine to produce an energy carrying molecule. This happens when the electrons get excited in photosystem I.
How does the electron transport chain work in photosynthesis?
The Electron Transport Chain. While at photosystem II and I, the electrons gather energy from sunlight. How do they do that? Chlorophyll, which is present in the photosystems, soaks up light energy. The energized electrons are then used to make NADPH. The electron transport chain is a series of molecules that accept or donate electrons easily.
Where do electrons travel in the electron transport chain?
Photosystem I was discovered first. Later, photosystem II was discovered and found to be earlier in the electron transport chain. But it was too late, the name stuck. Electrons first travel through photosystem II and then photosystem I. While at photosystem II and I, the electrons gather energy from sunlight. How do they do that?