Bio question from Kaplan subject test 2.

[fifi1314]

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question:
How many ATP are produced from 2 molecules of glucose using only substrate level phosphorylation.
Kaplan Answer: 8
Kaplan explanation: Substrate level phosphorylation occurs when ATP synthesis is directly coupled with theta degradation of glucose without the participation of an intermediate molecule such as NAD+. Degradation of one glucose
molecule yields a net of 2 ATP from glycolysis and 1 ATP for each turn of the citric acid cycle. Thus a total of 4 ATP are produced by substrate level phosphorylation for one molecule of glucose. For two molecules, it would be 8 ATP.

My question is: If each turn of glycolysis produce 2 ATP and each turn of citric acid cycle produce 1 ATP by 1 molecule glucose, totally ATP counts should be 3, How Come the Answer is 8, not 6 by 2 molecule of glucose?? Thanks alot!

 

[dl9006]

question:
How many ATP are produced from 2 molecules of glucose using only substrate level phosphorylation.
Kaplan Answer: 8
Kaplan explanation: Substrate level phosphorylation occurs when ATP synthesis is directly coupled with theta degradation of glucose without the participation of an intermediate molecule such as NAD+. Degradation of one glucose
molecule yields a net of 2 ATP from glycolysis and 1 ATP for each turn of the citric acid cycle. Thus a total of 4 ATP are produced by substrate level phosphorylation for one molecule of glucose. For two molecules, it would be 8 ATP.

My question is: If each turn of glycolysis produce 2 ATP and each turn of citric acid cycle produce 1 ATP by 1 molecule glucose, totally ATP counts should be 3, How Come the Answer is 8, not 6 by 2 molecule of glucose?? Thanks alot!

you forgot that 1 glucose gives you 2 pyruvate thus 2 atp from gtp.

the calculation:

2 net atp from glycolysis
+1 ATP(from kreb cycle)X2
= 4 atp for 1 glucose degradation

since it's 2 glucose, 4X2=8 atp

 

[fsddsms]

question:
How many ATP are produced from 2 molecules of glucose using only substrate level phosphorylation.
Kaplan Answer: 8
Kaplan explanation: Substrate level phosphorylation occurs when ATP synthesis is directly coupled with theta degradation of glucose without the participation of an intermediate molecule such as NAD+. Degradation of one glucose
molecule yields a net of 2 ATP from glycolysis and 1 ATP for each turn of the citric acid cycle. Thus a total of 4 ATP are produced by substrate level phosphorylation for one molecule of glucose. For two molecules, it would be 8 ATP.

My question is: If each turn of glycolysis produce 2 ATP and each turn of citric acid cycle produce 1 ATP by 1 molecule glucose, totally ATP counts should be 3, How Come the Answer is 8, not 6 by 2 molecule of glucose?? Thanks alot!

1 turn of citric acid cycle is 1 pyruvate. 2 pyruvate per glucose molecule. So you would do 2 turns of citric acid cycle to account for both pyruvate.

2 ATP net from glycolysis.
1 atp per turn of citric acid cycle x 2 turns = 2 atp

4 ATP per glucose molecule
8 ATP for 2 glucose molecule

 

[fifi1314]

Guys, Thanks alot!