Quizzes about Integrated Metabolism—Vitamins, Minerals, and Hormones - Part 2 (18 test - end)
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1. A 14-year-old African American adolescent has shown weight loss and increased thirst with fatigue and decreased athletic performance. His physician does a urinalysis and the reagent strip is strongly positive for glucose and ketones. A likely diagnosis of diabetes mellitus is made and the patient started on long-acting insulin at night with short-acting insulin at breakfast and lunch. Which of the following statements correctly describes insulin?
- It is an anabolic signal to cells that glucose is scarce.
- It is converted from proinsulin to insulin primarily following secretion from β-cells.
- It does not have a prohormone form.
- It is a small polypeptide composed of a single chain bridged by disulfide groups.
- Its action is antagonistic to that of glucagon.
2. Some individuals with diabetes mellitus are susceptible to rapid drops in blood sugar (hypoglycemia) with lethargy and potential seizures or Such diabetics are called “brittle” and require careful monitoring of glucose levels as proper insulin doses are titrated. Of the many actions of insulin, decrease in which of the following cellular activities best accounts for “brittleness” of certain diabetics?
- Plasma membrane transfer of glucose
- Glucose oxidation
- Formation of ATP, DNA, and RNA
3. The absorption of glucose from the gut into intestinal mucosal cells is coupled to Na+, K+-ATPase. In contrast, the movement of glucose from the intestinal epithelial cells into the submucosal bloodstream occurs through passive Given these facts, which of the following statements is most accurate?
- Cytosolic levels of glucose in intestinal mucosal cells are regulated by levels of glucose in skeletal muscle cells.
- Free glucose levels in the lumen of the intestine can never be higher than levels in intestinal cells.
- Plasma glucose levels are much higher than intestinal cell cytosolic levels of glucose.
- Levels of glucose in the intestinal lumen are always higher than those in the cytosol of intestinal epithelial cells.
- Levels of plasma glucose are approximately equal to levels in the cytosol of intestinal epithelial cells.
4. Several weight-loss diets are based on decreased carbohydrate intake to prevent stimulation of insulin secretion; insulin drives the feeling of hunger and also inhibits The suggested way of monitoring the success of low carbohydrate intake during fasting reflects the greatest increase in plasma concentration of which of the following?
- Palmitate, oleate (free fatty acids)
- Glucose, galactose
- Lactate, pyruvate
- Acetoacetate, β-hydroxybutyrate
5. Defects in the ability to oxidize fatty acids can be asymptomatic in the presence of frequent feeding; a therapy applied to all but the most severe long chain fatty acid oxidation disorders that are frequently lethal. In asymptomatic children with medium- or short-chain fatty acid oxidation defects, unintentional fasting due to infections can produce lethargy and even coma after 4 to 6 hours without food. A deficit in which of the following compounds in serum most likely causes these neurologic symptoms?
- Pyruvate and lactate
- Free fatty acids
- Propionate and methylmalonate
- Glucose and ketone bodies
6. A 25-year-old African American male seeks evaluation for increasing fatigue and muscle aches during He recalls avoiding athletics when young because he could not keep up with his peers and recently has embarked on an exercise program to help lose weight. Stress testing reveals normal cardiac function, but serial blood tests show increased serum lactic acid and ammonia levels when he is at rest. His physician postulates a mitochondrial DNA depletion disorder that affects mitochondrial function due to defects in mitochondrial DNA polymerase or tRNAs. Which of the following options: (1) list mitochondrial pathways that would explain the man’s blood findings, and (2) name a compound linking these pathways?
- Glycogenolysis, glycolysis, and glucose 1-P
- Glycogen synthesis, gluconeogenesis, and pyruvate
- Citric acid cycle, electron transport, and isocitrate
- Citric acid and urea cycles, and arginine
- Citric acid and urea cycles, and fumarate
7. Which of the following can be converted to an intermediate of either the citric acid cycle or the urea cycle?
8. An 18-year-old Caucasian female is admitted to the hospital for evaluation of extreme weight loss over the past 6 months. She has decreased subcutaneous tissue, sores on the back of her fingers, severe dental decay, and sparse Her parents report that she jogs each morning despite her weight loss, yet is preoccupied with food. A diagnosis of anorexia nervosa with bulimia is made and the female is started on a counseling program with intravenous feeding. Which of the following pathways would be least affected by this female’s catabolic state?
- β-Oxidation of fatty acids
- Citric acid cycle
9. A 46-year-old Caucasian female has had spells of irritability, headaches, and trembling when she does not eat for several hours. She is hospitalized overnight for metabolic studies that demonstrate a low blood sugar in the presence of adequate Which of the following would be an indicator of active gluconeogenesis?
- Increased urea production
- Increased conversion of alanine to pyruvate
- Increased conversion of acetyl-CoA to malonyl-CoA
- Increased conversion of oxaloacetate to citrate
- Increased conversion of glucose 6-phosphate to glucose 1-phosphate
10. A 60-year-old Egyptian male has a hemoglobin of 12 g/dL (13.5 lower limit of normal) during his annual checkup and was taking Bactrim (antibiotic with trimethoprim folate inhibitor and a sulfonamide) for a skin infection. The medical student who evaluated him had suggested a diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency (MIM*305900), recognizing the patient’s Mediterranean origin and exposure to sulfa antibiotics that can precipitate hemolysis in these individuals. The attending suggested G6PD deficiency would give much more severe symptoms of rapid hemolysis, severe anemia, and heart Given that PHI converts glucose 6-phosphate to fructose 6-phosphate and G6PD initiates the reverse conversion (with several subsequent enzymes), which of the following statements do these different clinical presentations support?
- Chemical conversions in metabolic pathways often use different enzymes and intermediates than reactions proceeding in the reverse direction.
- The reaction steps for degradative (catabolic) pathways are the exact reverse of those for biosynthetic sequence.
- Enzymes found in an anabolic pathway are never found in the corresponding catabolic pathway.
- The first steps in a metabolic pathway are rarely rate limiting or subject to regulation.
- Steps in both anabolic and catabolic pathways are usually reversible.
11. Which of the following statements is true in the well-fed state?
- NADPH production by the hexose monophosphate shunt is decreased.
- Acetoacetate is the major fuel for muscle.
- Glucose transport into adipose tissue is decreased.
- The major fuel used by the brain is glucose.
- Amino acids are utilized for glucose production.
12. The jinga bean, found in the jungles of Brazil, is unique in that it is composed almost exclusively of protein. Studies have shown that, immediately following a meal composed exclusively of jinga beans, which of the following occurs?
- A decreased release of epinephrine
- A complete absence of liver glycogen
- An increased release of insulin
- Ketosis caused by the metabolism of ketogenic amino acids
13. Approximately 3 hours following a well-balanced meal, blood levels of which of the following are elevated?
- Fatty acids
14. If a homogenate of liver cells is centrifuged to remove all cell membranes and organelles, which of the following enzyme activities will remain in the supernatant?
- Glucose-6-phosphate dehydrogenase
- Glycogen synthetase
- Acyl-CoA hydratase
- Hydroxybutyrate dehydrogenase
15. Which of the following enzymes is active in adipocytes following a heavy meal?
- Glycogen phosphorylase
- Glycerol kinase
- Hormone-sensitive triacylglyceride lipase
- Phosphatidate phosphatase
16. Which of the following statements correctly apply to energy metabolism?
- Fatty acids can be precursors of glucose.
- High energy levels turn on glycolysis.
- Pyruvate is committed to the citric acid cycle by acetylation through pyruvate dehydrogenase.
- Phosphorylation activates enzymes that store fat and glycogen.
- Guanosine triphosphate (GTP) is the major donor for enzyme phosphorylation.
17. Which of the following diseases reflects the loss of ability to move specific molecules between membrane-separated cellular compartments?
- McArdle phosphorylase disease
- Carnitine deficiency
- Methanol poisoning
- Ethylene glycol poisoning
18. Which of the following sets of blood values most closely correlates with a patient who has conducted a hunger strike for 1 month? The blood levels listed by option (a) represent the immediate postprandial state—choose option a if blood levels after the hunger strike will remain the same, or other options if they will change as
CONCENTRATION OF BLOOD FUELS (mM)