CELL RESPIRATION
THE KREBS CYCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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acetate
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pyruvate
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glucose
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citric acid
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Detailed explanation-1: -The acetyl CoA combines with 4-carbon compound oxaloacetate to form 6C citrate. In this process, 2 molecules of CO2 are released and oxaloacetate is recycled. Energy is stored in ATP and other high energy compounds like NADH and FADH2.
Detailed explanation-2: -First, acetyl CoA combines with oxaloacetate, a four-carbon molecule, losing the CoA group and forming the six-carbon molecule citrate.
Detailed explanation-3: -At the end of the Krebs cycle, the final product is oxaloacetic acid. This is identical to the oxaloacetic acid that begins the cycle. Now the molecule is ready to accept another acetyl-CoA molecule to begin another turn of the cycle.
Detailed explanation-4: -The remaining steps of the Krebs cycle regenerate oxaloacetic acid from succinate: Succinate is oxidized to form the four-carbon molecule called fumerate.
Detailed explanation-5: -Explanation: Acetyl CoA formed from pyruvic acid enters Krebs’ cycle by combining with oxaloacetic acid. OAA and acetyl CoA form a 6-carbon compound citric acid as first product of the cycle. So, the correct answer is ‘Citrate’.