8.2 (Energy Metabolism) Flashcards
State the location of the light-dependent reactions of photosynthesis.
Occurs in the intermembrane space of the thylakoids and the thylakoid membrane
What is included in the light-dependent reactions of photosynthesis?
Photoactivation Photolysis Electron transport Chemiosmosis ATP synthesis Reduction of NADP to NADPH + H+
State that the light-dependent reactions convert light energy into chemical energy in the form of ATP and NADH.
Light-dependent reactions convert light energy into chemical energy in the form of ATP and NADH
State the location of the light-independent reactions of photosynthesis.
The stroma
What is included in the light-independent reactions of photosynthesis?
Carbon fixation Carboxylation of RuBP Production of TP (triose phosphate) ATP and NADPH as energy sources ATP used to regenerate RuBP ATP used to produce carbohydrates
Define photosystem and reaction center.
Photosystems are chlorophyll molecules and other accessory pigments which are organized into photosystems
Reaction center: a complex of several proteins, pigments, and other co-factors that together execute the primary energy conversion reactions of photosynthesis
State that the light- reactions of photosynthesis begin at Photosystem II.
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Outline the process of photoactivation of the reaction center chlorophyll.
Chlorophyll molecules and other accessory pigments are organized into photosystems. Photosystems are located in the thylakoid membrane (along with electron carriers and ATP synthase enzymes). Photosystems contain pigment molecules arranged to harvest light energy and channel it to the reaction center. (Light is a requirement for photosynthesis to occur). When a chlorophyll molecule absorbs light, the energy from light excites an electron, making it into a high-energy electron. The energy is transferred via pigment molecules to the reaction center. Located in the reaction center is a special pair of chlorophyll molecules. Electrons within the reaction center chlorophylls are excited. These excited electrons can be donated two at a time from an electron center chlorophyll to an electron acceptor. This is called photoactivation.
State that in photoactivation at Photosystem II, the reaction center chlorophyll is oxidized and the plastoquinone (Pq) is reduced.
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State that to replace the electrons lost during photoactivation, the reaction center chlorophyll takes electrons by splitting water.
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Draw a cross section of the thylakoid membrane to show the path of transfer of excited electrons, inclusive of Photosystem II, ATP synthase, an electron transport chain (with Pq first) and Photosystem II.
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tate that electrons pass from plastoquinone (Pq) through a chain of electron carrier molecules.
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State that the energy released by the movement of electrons is used to pump protons across the thylakoid membrane, from the stroma into the thylakoid lumen.
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State that the result of the electron transport chain is a proton gradient, with a high concentration of protons in the thylakoid lumen.
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State that in chemiosmosis, ATP is generated as protons move down their concentration gradient through ATP synthase.
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