Step 1

Biochemistry 17

A 20-year-old, Gravida 1, Para 0 woman at 16 weeks’ gestation presents to the obstetrician’s office to discuss her amniocentesis test results. Her past medical history is unremarkable. Her father has a history of recurrent foot pain and kidney stones. Her vital signs are blood pressure 114/78 mm Hg and heart rate of 82 beats/minute. Fetal heartbeat is heard using fetal Doppler and has a normal rate of 143 beats/minute. The obstetrician explains that the amniocentesis revealed a deficiency in hypoxanthine-guanine phosphoribosyltransferase (HPRT) activity.

Which of the following statements is correct regarding the action of this enzyme?

  • A) It converts guanine and hypoxanthine into inosine monophosphate with help of nicotinamide adenine dinucleotide (NADH)
  • B) It converts hypoxanthine and guanine into xanthine
  • C) It converts hypoxanthine into guanine
  • D) Phosphoribosyl pyrophosphate (PRPP) is needed for the conversion of guanine into guanosine monophosphate
  • E) Thiamine is needed for its action


Husban Hamil


Dr. Ted O'Connell

Last updated

Nov 08, 2023

Our Other Products: