Question

1) Which of the following can be a substrate for ribose 5-phosphate synthesis when glucose 6-phosphate dehydrogenase is deficient?

1-Galactose 1-Phosphate

2-Pyruvate

3-Citrate

4-UTP-glucose

5-Fructose 6-phosphate

2) A patient becomes. fatigued after performing strenuous exercise. Assays from a muscle biopsy revealed slightly elevated glycogen levels but the glycogen phosphorylase activity is less responsive to calcium activation. Which enzyme is most likely affected in this patient?

1-Glycogen debranching enzyme

2-Glycogen phosphatase

3-Glycogen phosphorylase kinase

4- Glycogen synthetase O Glycogen branching enzyme

Answer 1

Question 1) option 5, fructose 6 phosphate

This is a intermediate of HMP pathway. This fructose 6 pathway enter in to HMP pathway , by reversible reaction to form ribose 5 phosphate.

Question 2) option 3 , glycogen phosphorylase kinase.

Glycogen phosphorylase kinase is made up of 4 subunit. Alpha , beta , gamma and delta. Delta subunit binds to calcium, and get activated this further activate glycogen phosphorylase. This regulation is important in muscle , during muscle contraction calcium or released which activate, phosphorylase kinase and lead to activation of glycogen phosphorylase. So in case of mutaion in phosphorylase kinase , there will be no activation of glycogen phosphorylase and no release of glucose and patient will have fatigue after strenuous exercise.