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Free notes, MCQs, tables & flowcharts for USMLE Step 3 Biochemistry
Researchers are experimenting with hormone levels in mice in fasting and fed states. To test hormone levels in the fed state, the mice are given an oral glucose load and various hormones are measured in a blood sample. Researchers are most interested in the hormone whose blood levels track evenly with C-peptide levels. The hormone the researchers are most interested in is responsible for which of the following actions in the body?
AProtein catabolism
BFatty acid breakdown
CFatty acid synthesis
DKetogenesis
ELipolysis
An investigator is studying the effect of extracellular pH changes on the substrates for the citric acid cycle. Which of the following substances is required for the reaction catalyzed by the enzyme marked by the arrow in the overview of the citric acid cycle?
APantothenic acid
BNiacin
CThiamine
DRiboflavin
ELipoic acid
A 4-day-old boy is brought to the physician by his mother because of vomiting, irritability, and poor feeding. Pregnancy and delivery were uncomplicated. Physical examination shows increased muscle tone in all extremities. He appears lethargic. His diapers emit a caramel-like odor. Urine studies are positive for ketone bodies. Supplementation of which of the following is most likely to improve this patient's condition?
ATyrosine
BCysteine
CTetrahydrobiopterin
DThiamine
ELeucine
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