Plant-Physiologyphotosynthesis-3
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Light reactions occur in the thylakoid membranes of chloroplasts.
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Both, PSII and PSI, are involved in the light reactions.
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Photosystems contain all the pigments (except one molecule of chlorophyll a) forming a light harvesting complex, also known as antennae complex
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Pigments absorb light in the form of photons and this energy is used to excite the electrons to higher energy levels.
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Site of photolysis of water is PSII, releasing oxygen, electrons, and protons (H+).
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The products of the light reaction (ATP and NADPH) are used in Dark reaction for carbohydrate synthesis.
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The reduction phase of the Calvin cycle is considered as reverse of glycolysis.
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Chemiosmotic hypothesis explains how the electron transport is linked to the generation of ATP.
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Excited electrons from PSII are transferred through protein complexes in the thylakoid membrane.
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This creates a proton gradient across the thylakoid membrane.
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The breakdown of the proton gradient generates ATP.
