A 4-month-old boy is brought to his pediatrician for a well-child visit. His parents have noticed that he has had poor growth compared to his older siblings. The boy was delivered vaginally after a normal pregnancy. His temperature is 98.8°F (37.1°C), blood pressure is 98/68 mmHg, pulse is 88/min, and respirations are 20/min. On exam, his abdomen appears protuberant, and the boy appears to have abnormally enlarged cheeks. A finger stick reveals that the patient’s fasting blood glucose is 50 mg/dL. On further laboratory testing, the patient is found to have elevated blood lactate levels, as well as no response to a glucagon stimulation test. What enzymatic defect is most likely present?
AAlpha-1,4-glucosidase
BGlycogen synthase
CAlpha-1,6-glucosidase
DGlucose-6-phosphatase
EGlycogen phosphorylase
A 30-year-old woman presents to her physician for her annual checkup. She has diabetes mellitus, type 1 and takes insulin regularly. She reports no incidents of elevated or low blood sugar and that she is feeling energetic and ready to face the morning every day. Her vital signs and physical are normal. On the way home from her checkup she stops by the pharmacy and picks up her prescription of insulin. Later that night she takes a dose. What is the signaling mechanism associated with this medication?
AIncreased concentration intracellular cAMP
BIncreased permeability of the cell membrane to negatively charged molecules
CActivation of tyrosine kinase
DRapid and direct upregulation of enzyme transcription
EIncreased permeability of the cell membrane to positively charged molecules
A scientist is trying to design a drug to modulate cellular metabolism in the treatment of obesity. Specifically, he is interested in understanding how fats are processed in adipocytes in response to different energy states. His target is a protein within these cells that catalyzes catabolism of an energy source. The products of this reaction are subsequently used in gluconeogenesis or β-oxidation. Which of the following is true of the most likely protein that is being studied by this scientist?
AIt is stimulated by epinephrine
BIt is inhibited by glucagon
CIt is inhibited by acetylcholine
DIt is inhibited by cortisol
EIt is stimulated by insulin
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