3 The passage of electrons is accompanied by the formation of a proton gradient

3 the passage of electrons is accompanied by the

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3. The passage of electrons is accompanied by the formation of a proton gradient across the inner mitochondrial membrane or the thylakoid membrane of chloroplasts, with the membrane(s) separating a region of high proton concentration from a region of low proton concentration. In prokaryotes, the passage of electrons is accompanied by the outward movement of protons across the plasma membrane. 4. The flow of protons back through membrane-bound ATP synthase by chemiosmosis generates ATP from ADP and inorganic phosphate. 5. In cellular respiration, decoupling oxidative phosphorylation from electron transport is involved in thermoregulation. The names of the specific electron carriers in the ETC are beyond the scope of the course and the AP Exam. h. Free energy becomes available for metabolism by the conversion of ATP à ATP which is coupled to many steps in metabolic pathways. Essential knowledge 4.A.2: The structure and function of subcellular components, and their interactions, provide essential cellular processes. d. Mitochondria specialize in energy capture and transformation. [See also 2.A.2 , 2.B.3 ] Evidence of student learning is a demonstrated understanding of each of the following: 1. Mitochondria have a double membrane that allows compartmentalization within the mitochondria and is important to its function. 2. The outer membrane is smooth, but the inner membrane is highly convoluted, forming folds called cristae. 3. Cristae contain enzymes important to ATP production; cristae also increase the surface area for ATP production. g. Chloroplasts are specialized organelles found in algae and higher plants that capture energy through photosynthesis. [See also 2.A.2, 2 B.3 ] Evidence of student learning is a demonstrated understanding of each of the following: 1. The structure and function relationship in the chloroplast allows cells to capture the energy available in sunlight and convert it to chemical bond energy via photosynthesis. 2. Chloroplasts contain chlorophylls, which are responsible for the green color of a plant and are the key light-trapping molecules in photosynthesis. There are several types of chlorophyll, but the predominant form in plants is chlorophyll a . 20
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The molecular structure of chlorophyll a is beyond the scope of the course and the AP Exam. 3. Chloroplasts have a double outer membrane that creates a compartmentalized structure, which supports its function. Within the chloroplasts are membrane-bound structures called thylakoids. Energy- capturing reactions housed in the thylakoids are organized in stacks, called “grana,” to produce ATP and NADPH2, which fuel carbon- fixing reactions in the Calvin-Benson cycle. Carbon fixation occurs in the stroma, where molecules of CO2 are converted to carbohydrates.
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