Multiple Choice
Which steps of glycolysis are considered irreversible under physiological conditions?
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Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway
Glycolysis 1
Multiple Choice
During glycolysis (from one molecule of glucose to two molecules of pyruvate), what is the net number of ATP molecules produced directly by substrate-level phosphorylation?
A
0 ATP (net)
B
4 ATP (net)
C
36 ATP (net)
D
2 ATP (net)
Verified step by step guidance1
Understand that glycolysis converts one molecule of glucose into two molecules of pyruvate through a series of enzymatic reactions.
Identify the steps in glycolysis where ATP is produced directly by substrate-level phosphorylation. These occur during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and phosphoenolpyruvate to pyruvate.
Note that each glucose molecule produces two molecules of glyceraldehyde-3-phosphate, so the ATP-producing steps happen twice per glucose molecule.
Calculate the total ATP produced by substrate-level phosphorylation: 2 ATP molecules are generated per glyceraldehyde-3-phosphate, so multiply by 2 for the two molecules formed from one glucose.
Subtract the ATP molecules consumed earlier in glycolysis (specifically in the phosphorylation steps of glucose and fructose-6-phosphate) to find the net ATP yield from substrate-level phosphorylation.
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