alleryStart learning →Which enzyme catalyses the very first step of glycolysis by phosphorylating glucose?
AThe enzyme aldolase
BThe enzyme enolase
CThe enzyme hexokinase
DThe enzyme pyruvate kinase
Answer & Solution
Correct answer: C. The enzyme hexokinase
1. The first step of glycolysis is catalysed by hexokinase, an enzyme with broad specificity for six-carbon sugars.
2. Hexokinase phosphorylates glucose using adenosine triphosphate as the phosphate source.
3. The product is glucose-6-phosphate, a more reactive form of glucose.
4. Pyruvate kinase acts at the tenth and final step, so it cannot be the first.
_Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.2 Glycolysis_
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