Glycolysis — MCQs

An investigator is conducting an experiment to study different pathways of glucose metabolism. He obtains cells cultured from various tissues to study the effect of increased extracellular glucose concentration. Following the incubation of these cells in 5% dextrose, he measures the intracellular fructose concentration. The concentration of fructose is expected to be highest in cells obtained from which of the following tissues?

A 12-year-old boy and his siblings are referred to a geneticist for evaluation of a mild but chronic hemolytic anemia that has presented with fatigue, splenomegaly, and scleral icterus. Coombs test is negative and blood smear does not show any abnormal findings. An enzymatic panel is assayed, and pyruvate kinase is found to be mutated on both alleles. The geneticist explains that pyruvate kinase functions in glycolysis and is involved in a classic example of feed-forward regulation. Which of the following metabolites is able to activate pyruvate kinase?

A 12-year-old male presents to the pediatrician after two days of tea-colored urine which appeared to coincide with the first day of junior high football. He explains that he refused to go back to practice because he was humiliated by the other players due to his quick and excessive fatigue after a set of drills accompanied by pain in his muscles. A blood test revealed elevated creatine kinase and myoglobulin levels. A muscle biopsy was performed revealing large glycogen deposits and an enzyme histochemistry showed a lack of myophosphorylase activity. Which of the following reactions is not occurring in this individual?

A patient presents to the emergency room in an obtunded state. The patient is a known nurse within the hospital system and has no history of any medical problems. A finger stick blood glucose is drawn showing a blood glucose of 25 mg/dL. The patient's daughter immediately arrives at the hospital stating that her mother has been depressed recently and that she found empty syringes in the bathroom at the mother's home. Which of the following is the test that will likely reveal the diagnosis?

A 12-month-old boy is brought to the physician by his mother for a well-child examination. He was delivered at term after an uncomplicated pregnancy. His mother says he is breastfeeding well. He is at the 50th percentile for height and 65th percentile for weight. Physical examination shows no abnormalities. Urinalysis shows 3+ reducing substances. Compared to a healthy infant, giving this patient apple juice to drink will result in increased activity of which of the following enzymes?

A 33-year-old woman, gravida 1, para 0, at 26 weeks' gestation comes to the physician for a routine prenatal examination. Her pregnancy has been uneventful. Physical examination shows a uterus consistent in size with a 26-week gestation. She is given an oral 50-g glucose load; 1 hour later, her serum glucose concentration is 116 mg/dL. Which of the following most likely occurred immediately after the entrance of glucose into the patient's pancreatic beta-cells?

A 3-month-old girl is brought to the emergency department by her parents after she appeared to have a seizure at home. On presentation, she no longer has convulsions though she is still noted to be lethargic. She was born through uncomplicated vaginal delivery and was not noted to have any abnormalities at the time of birth. Since then, she has been noted by her pediatrician to be falling behind in height and weight compared to similarly aged infants. Physical exam reveals an enlarged liver, and laboratory tests reveal a glucose of 38 mg/dL. Advanced testing shows that a storage molecule present in the cells of this patient has abnormally short outer chains. Which of the following enzymes is most likely defective in this patient?

A 63-year-old man is brought in by ambulance after a bar fight. Witnesses report that he is a bar regular and often drinks several shots of hard liquor throughout the night. The emergency department recognizes him as a local homeless man with a long history of alcohol abuse. During the initial workup in the ED, he has a prolonged seizure and dies. An autopsy is performed that shows an enlarged heart with severe calcified atherosclerotic coronary arteries. Evaluation of his brain shows atrophic mammillary bodies with brown-tan discoloration. Which of the following tests would have most likely produced an abnormal result in vivo with respect to his nervous system findings on autopsy?

A 3-month-old boy is brought to the emergency department by his mother after a seizure at home. The mother is not sure how long the seizure lasted, but says that the boy was unresponsive and had episodes of stiffness and jerking of his extremities throughout the episode. The mother states that the boy has not seemed himself for the past several weeks and has been fussy with feeds. He does not sleep through the night. He has not had any recent infections or sick contacts. On exam, the boy is lethargic. His temperature is 99.5°F (37.5°C), blood pressure is 70/40 mmHg, and pulse is 120/min. He has no murmurs and his lungs are clear to auscultation bilaterally. His abdomen appears protuberant, and his liver span is measured at 4.5 cm below the costal margin. Additionally, the boy has abnormally enlarged cheeks. A finger stick in the ED reveals a blood glucose level of 35 mg/dL. What would this patient’s response to a fasting-state glucagon stimulation test most likely be, and what enzyme defect does he have?

A newborn infant presents with severe weakness. He was born to a G1P1 mother at 40 weeks gestation with the pregnancy attended by a midwife. The mother's past medical history is unremarkable. She took a prenatal vitamin and folic acid throughout the pregnancy. Since birth, the child has had trouble breastfeeding despite proper counseling. He also has had poor muscle tone and a weak cry. His temperature is 99.5°F (37.5°C), blood pressure is 57/38 mmHg, pulse is 150/min, respirations are 37/min, and oxygen saturation is 96% on room air. Physical exam reveals poor muscle tone. The patient's sucking reflex is weak, and an enlarged tongue is noted. An ultrasound is performed, and is notable for hypertrophy of the myocardium. Which of the following is the most likely diagnosis?