- Select ALL the TRUE statements regarding glycolysis
A.
Glycolysis produces 32-34 molecules of ATP per glucose molecule
B.
Glycolysis occurs within the mitochondrial matrix of both prokaryotes and eukaryotes.
C.
During the conversion stages of 3-carbon molecules that result in forming pyruvic acid (pyruvate), NAD+ is reduced to NADH.
D.
The pyruvate made during glycolysis can be used either in the Krebs cycle or fermentation, and the NADH+ is used in the electron transport chain.
E.
Two molecules of ATP are utilized to fuel the reactions of glycolysis.
F.
Glycolysis is the breakdown of glucose, which is a key part of the metabolism of both aerobic and anaerobic organisms.
The Correct Answer and Explanation is:
Correct Answers: C, D, E, and F
Explanation
Glycolysis is a fundamental metabolic pathway that breaks down glucose (a 6-carbon sugar) into two molecules of pyruvate (3-carbon compounds). This process occurs in the cytoplasm of both prokaryotic and eukaryotic cells—not in the mitochondrial matrix—making statement B false.
Statement A is incorrect because glycolysis itself only produces a net gain of 2 ATP molecules per glucose, not 32–34. The larger ATP yield (about 32–34 ATP) comes from cellular respiration as a whole, including the Krebs cycle and the electron transport chain, but not from glycolysis alone.
Statement C is true: During glycolysis, specifically in the energy payoff phase, the 3-carbon intermediates (like glyceraldehyde-3-phosphate) are oxidized, and NAD+ is reduced to NADH. This is a key step, as the captured electrons will later be used in the electron transport chain (in aerobic organisms).
Statement D is also true: After glycolysis, pyruvate has two potential fates. Under aerobic conditions, it enters the Krebs cycle for further breakdown and energy extraction. Under anaerobic conditions, it may undergo fermentation (e.g., lactic acid or alcohol fermentation). Meanwhile, NADH produced in glycolysis can be used in the electron transport chain to produce more ATP, but only if oxygen is present.
Statement E is correct: Glycolysis requires an initial investment of 2 ATP molecules during its early steps (energy investment phase) to phosphorylate glucose and its intermediates, which helps drive the later energy-releasing reactions.
Statement F is correct: Glycolysis is central to both aerobic and anaerobic metabolism, making it one of the most ancient and conserved pathways in biology. It provides a quick supply of energy and intermediates needed for other pathways.
Thus, C, D, E, and F are the true statements.
