Metabolism & Bioenergetics MCAT Practice Question
A 3-year-old boy is brought to the emergency department with altered mental status and severe diaphoresis 30 minutes after consuming apple juice at a family gathering. Vital signs show tachycardia and hypotension. Laboratory studies reveal blood glucose of 32 mg/dL, elevated transaminases (ALT 280 U/L, AST 310 U/L), and hyperuricemia. Genetic testing confirms hereditary fructose intolerance (HFI) due to aldolase B deficiency. The patient's mother reports he has previously experienced similar episodes after consuming fruits and honey. Which of the following best explains the acute hypoglycemia in this patient?
Answer choices
- AFructose-1-phosphate accumulation depletes the free phosphate pool, impairing ATP regeneration and inhibiting gluconeogenesisCorrect answer
- BFructose-1-phosphate directly inhibits glucose-6-phosphatase through allosteric feedback inhibition
- CAldolase B deficiency prevents conversion of any aldol substrates to glucose precursors
- DFructose competitively inhibits hepatic glycogen phosphorylase, blocking glycogenolysis
- EAccumulated fructose-1-phosphate traps inorganic phosphate in the nucleus, preventing cytoplasmic ATP synthesis
- FHexokinase is competitively inhibited by fructose-1-phosphate, preventing glucose phosphorylation and trapping glucose-6-phosphate
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