Before the carbons coming from glycolysis can enter the TCA cycle, they must be converted to acetyl-CoA by what enzyme complex? What are its effector molecules? Do all the carbons from a glucose molecule enter the TCA cycle?
Ans. #1. Glucose is first converted into pyruvate through glycolysis.
Pyruvate in converted into acetyl-CoA by the enzyme pyruvate dehydrogenase (PDH) complex before it can enter citric acid cycle.
#2. Any molecule that binds to the allosteric site of the enzyme and modulate the rate of catalysis is called an effector.
For example, NADH and acetyl-CoA also acts as effector of the enzyme as they, when present in higher concentration, binds to the enzyme and inhibit its catalysis.
#3. No.
During concertation of pyruvate (3C) into acetyl-CoA (2C), there is loss of one C-atom as CO2. So, only 2 C-atoms per pyruvate enter TCA. Or, only 4 C-atoms per glucose molecule enter TCA.
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