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Where do electrons come from in light reactions?
The light dependent reactions happen first. The electron that starts the whole photosynthetic cycle originates from chlorophyll, the green pigment found in the chloroplasts of plants. The energy in sunlight electronically excites the chlorophyll molecule and one of its electrons is released.
How are electrons produced in photosynthesis?
The light reactions of photosynthesis use energy from photons to generate high-energy electrons (Figure 19.2). These electrons are used directly to reduce NADP+ to NADPH and are used indirectly through an electron-transport chain to generate a proton-motive force across a membrane.
Where do electrons come from in photosynthesis?
In (a) photosystem II, the electron comes from the splitting of water, which releases oxygen as a waste product. In (b) photosystem I, the electron comes from the chloroplast electron transport chain. The two photosystems absorb light energy through proteins containing pigments, such as chlorophyll.
Where do photosystem 1 electrons come from?
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.
What is produced during the light reaction?
The Light Reactions The energy is then temporarily transferred to two molecules, ATP and NADPH, which are used in the second stage of photosynthesis. ATP and NADPH are generated by two electron transport chains. During the light reactions, water is used and oxygen is produced.
Where does the electron in photosynthesis come from?
Photosynthesis consists of two main parts, the light dependent reactions and the light independent reactions. The light dependent reactions happen first. The electron that starts the whole photosynthetic cycle originates from chlorophyll, the green pigment found in the chloroplasts of plants.
How are electrons transferred from the ground to the excited state?
These arrows signify that the special pigments P 680 and P 700 receive light energy from the light-harvesting chlorophyll-protein molecules and are raised in energy from their ground state to excited states. In their excited state, these pigments are extremely strong reducing agents that quickly transfer electrons to the first acceptor.
What happens to electrons in the pathway of electrons?
The pathway of electrons. Each time a P 680 or P 700 molecule gives up an electron, it returns to its ground (unexcited) state, but with a positive charge due to the loss of the electron. These positively charged ions are extremely strong oxidizing agents that remove an electron from a suitable donor.
What happens when a molecule gives up an electron?
Each time a P 680 or P 700 molecule gives up an electron, it returns to its ground (unexcited) state, but with a positive charge due to the loss of the electron. These positively charged ions are extremely strong oxidizing agents that remove an electron from a suitable donor.
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