In the light reactions of photosynthesis, electrons within the pigment molecules that are embedded in the plasma membranes of the thylakoids are hit by photons of sunlight. This dramatically increases the energy in these electrons. When photons of light strike electrons in other kinds of molecules, the electrons are raised to high energy levels, but immediately drop back down to their ground states, re-emitting the photons. However, in the light reactions, an excited electron is passed to an electron acceptor molecule before it can drop back down to its ground state. The excited electron is then passed from the primary electron receptor to the electron transport chain and eventually ends up as part of a glucose molecule. If the pigments in the thylakoid are continually passing their electrons to other molecules, how do the pigments replace their missing electrons?
In the light reactions of photosynthesis, electrons within the pigment molecules that are embedded in the plasma membranes of the thylakoids are hit by photons of sunlight. This dramatically increases the energy in these electrons. When photons of light strike electrons in other kinds of molecules, the electrons are raised to high energy levels, but immediately drop back down to their ground states, re-emitting the photons. However, in the light reactions, an excited electron is passed to an electron acceptor molecule before it can drop back down to its ground state. The excited electron is then passed from the primary electron receptor to the electron transport chain and eventually ends up as part of a glucose molecule. If the pigments in the thylakoid are continually passing their electrons to other molecules, how do the pigments replace their missing electrons?
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To replace the missing electrons, an enzyme removes the two hydrogen atoms from a water molecule. Each H atom provides one electron. These electrons replace the electrons that were passed into the electron transport chain. |
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After the excited electrons travel through the electron transport chain, their energy level is low and they come back to where they started. In other words, the electrons travel in a circuit.
To replace the missing electrons, an enzyme removes the two hydrogen atoms from a water molecule. Each H atom provides one electron. These electrons replace the electrons that were passed into the electron transport chain. |
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A neutron is actually a combination of a proton and an electron (this is why a neutron is neutral). When the pigment needs electrons, it breaks its neutrons apart to get the electron. |
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