Question 1

Where does glycolysis occur?

Accepted Answer

All ten enzymatic reactions of glycolysis occur in the cytoplasm, usually described as the cytosol. The pathway does not directly consume oxygen, so its ten reactions do not change when oxygen availability changes.

Question 2

How many ATP molecules are produced per glucose in glycolysis?

Accepted Answer

Four ATP molecules are produced in the payoff reactions through phosphoglycerate kinase and pyruvate kinase. Since two ATP were earlier consumed by hexokinase and phosphofructokinase, the net yield is two ATP per glucose.

Question 3

Why are there two three-carbon molecules after glycolysis starts splitting?

Accepted Answer

Fructose-1,6-bisphosphate is cleaved into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. Triose isomerase converts dihydroxyacetone phosphate into glyceraldehyde-3-phosphate, so the pathway continues with two G3P molecules per glucose.

Question 4

What is the role of fermentation?

Accepted Answer

Fermentation regenerates NAD+ from NADH. This allows glyceraldehyde-3-phosphate dehydrogenase to keep operating, so glycolysis can continue under oxygen-limited conditions. Fermentation itself produces no ATP beyond the two ATP obtained from glycolysis.

Question 5

What are the final products of glycolysis per glucose?

Accepted Answer

Each glucose produces two three-carbon pyruvate molecules, two NADH and two H+, with a net gain of two ATP. The later destination of pyruvate depends on the respiratory conditions, but the ten glycolytic reactions themselves remain unchanged.

Glycolysis & Fermentation 3D Lab

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Practice