The starting substance of the Krebs cycle, which is regenerated at the end of the cycle, is:
a, acetyl CoA
b. pyruvic acid
c. oxaloacetic acid
d. citric acid
its not a. acetyl CoA, because i put that as my answer and got it wrong. please help me. thanks!
2006-12-21 12:21:43 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Biology
please give an explanation too thanks!
2006-12-21 12:27:23 · update #1
C. Oxaloacetic acid.
The starting substance for Citric acid cycle is the Acetyl CoA and Oxaloacetic acid. The reason being Acetyl CoA not your answer is because your question stated that IT IS GENERATED AT THE END OF THE CYCLE. Acetyl CoA comes from Pyruvate. It is NOT generated at the end of the cycle.
Pyruvic acid is not even in the cycle. So that is out.
Citric acid is the product of Acetyl CoA reacting with Oxaloacetic acid.
In the case of oxaloacetic acid, you do get back that because at the end of the cycle, during the last step; dehydrogenation. The malatic acid is being dehydrogenized to form the oxaloacetic acid through the enzyme malate dehydrogenase. That is how oxaloacetic acid is gotten back.
2006-12-21 13:39:41 · answer #1 · answered by PIPI B 4 · 2⤊ 0⤋
Oxaloacetic acid
2006-12-21 20:44:29 · answer #2 · answered by <3DA<3 1 · 0⤊ 0⤋
c
2006-12-21 20:25:00 · answer #3 · answered by Nick F 6 · 0⤊ 0⤋