Question

1. Hers disease results from an absence of liver glycogen phosphorylase. Which of the following is NOT likely to be a symptom of an individual with Hers disease?

	A.	hypolipidaemia
	B.	lethargic between meals
	C.	enlargement of the liver
	D.	hypoglycemic

2. If the concentration of ATP is low, the availability of glucose and acetyl-CoA is high, and no other metabolic demands are made on the cell, what is the most likely fate of oxaloacetate?

	A.	Used for gluconeogenesis
	B.	Used to produce ketone bodies
	C.	Used to synthesize amino acids
	D.	Used in the citric acid cycle

3. Amino acid degradation:

	A.	of cellular protein occurs during the well-fed state.
	B.	uses transaminases to transfer all excess nitrogen to fumarate.
	C.	leads to the production of urea by terrestrial vertebrates.
	D.	requires no energy.

Answer 1

Question 1

Answer: Hers disease is a glycogen storage disease VI and is caused by deficiency of liver glycogen phosphorylase enzyme. Glycogen phosphorylase is a rate limiting enzyme in glycogenolysis and is involved in the release of glucose-1-phosphate from glycogen. Deficiency of this enzyme leads to inhibition of glycogen breakdown and glucose release. Glycogen accumulates in the liver, leading to enlargement of liver and reduced glucose in the blood (hypoglycemic). As glucose is not released from glycogen, lethargy between meals occurs. Hence, options B, C and D are the symptoms of the Hers disease. Hers disease cause ketogenesis and an increase in the ketone bodies and lipids (Hyperlipidemia) in the liver. Hence, option A, hypolipidemia is not a symptom of her disease. The correct answer is option A.

Question 2

Answer: As the ATP concentration is low, oxaloacetate enters citric acid cycle to generate ATP via electron transport chain. Hence, option D is the correct answer. As the concentration of glucose and acetyl CoA are high, gluconeogenesis (formation of glucose from non-carbohydrate substrates) and ketone bodies production does not occur. Hence, option A and B are incorrect. Synthesis of amino acid requires ATP. As the ATP concentration is low, oxaloacetate is not used for amino acid synthesis. Hence, option C is the incorrect answer.