When night feedings are discontinued, an infant shows symptoms of lethargy, unconsciousness, convulsions and sweating. When a sample of liver taken from this infant is incubated with 14C-lactate, the 14C label is found in glucose, but not in glycogen. Galactose metabolism is normal. Which enzyme might be deficient? a) glycogen synthase b) phosphoglucomutase c) phosphorylase d) triose isomerase e) glucokinase

Question

Rhett Salazar

Biology

13 November, 03:22

When night feedings are discontinued, an infant shows symptoms of lethargy, unconsciousness, convulsions and sweating. When a sample of liver taken from this infant is incubated with 14C-lactate, the 14C label is found in glucose, but not in glycogen. Galactose metabolism is normal. Which enzyme might be deficient? a) glycogen synthase b) phosphoglucomutase c) phosphorylase d) triose isomerase e) glucokinase

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Answers (1)

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Kevin Hines · Answer 1

The correct answer is a) glycogen synthase.

Explanation:

Glycogen synthase catalyzes the conversion of glucose to glycogen by a process known as glycogenesis. The so formed glycogen is stored in liver and muscle.

In this question the 14C label is not found is glycogen because most of the glycogen molecules are broken down into glucose molecules to meet the body"s glucose demand during the discontinuous night feedings.

That"s why most of the carbon skeleton are busy to synthesize glucos rather than glycogen. As a result 14C label is found only in glucose.