CELL RESPIRATION
THE KREBS CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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The mitochondrial intermembrane space
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The cytosol and mitochondrial matrix
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The cytosol
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The endoplasmic reticulum
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Detailed explanation-1: -During cellular respiration, where is NADH produced? Explanation: NADH is produced during glycolysis, which occurs in the cytoplasm. NADH is also produced during the Krebs cycle, which occurs in the mitochondrial matrix.
Detailed explanation-2: -NADH equivalents generated in the cytoplasm via glycolysis are transferred to the mitochondria by shuttling mechanisms such as the malate-aspartate shuttle, in which NADH in the cytosol is oxidized to NAD+ and NAD+ in mitochondria is reduced to NADH.
Detailed explanation-3: -During respiratory glucose dissimilation, eukaryotes produce cytosolic NADH via glycolysis. This NADH has to be reoxidized outside the mitochondria, because the mitochondrial inner membrane is impermeable to NADH.
Detailed explanation-4: -In eukaryotic cells, the theoretical maximum yield of ATP generated per glucose is 36 to 38, depending on how the 2 NADH generated in the cytoplasm during glycolysis enter the mitochondria and whether the resulting yield is 2 or 3 ATP per NADH.
Detailed explanation-5: -Although most NADH molecules are produced by TCA cycle inside of mitochondria, those by glycolysis are in cytosol. Mitochondrial inner membrane does not have any direct NADH transport system.