Exam 1 Practice Quiz Flashcards
Which of the following statements accurately characterizes fetal hemoglobin (HgbF)?
- Lower affinity for oxygen (O2) relative to adult Hgb
- Exhibits no Bohr effect
- Lower affinity for 2,3-bisphosphoglycerate (BPG) relative to adult Hg
- Completely replaced prior to birth
- Includes two β-subunits and two γ-subunits
Lower affinity for 2,3-bisphosphoglycerate (BPG) relative to adult Hg
A 7-year-old boy arrives at the emergency department asleep in his father’s arms. The boy’s mother explains that the boy spent the night throwing up and experiencing severe diarrhea. She is concerned about the vomiting and his inability to stay awake. History indicates the boy was healthy yesterday, but became ill at dinnertime after spending time playing in the basement of their apartment complex that afternoon.
Further inquiry reveals that an exterminator had been hired to take care of a rat problem in the apartment. He had used a poison (Rotenone) that blocks complex I in the respiratory chain of oxidative phosphorylation. The boy is pale and not cyanotic. An analysis of this patient’s metabolism would likely indicate impaired function of which of the following enzymes?
- Succinate dehydrogenase
- Glucose-6-phosphate dehydrogenase
- PDH complex
- PFK
- Pyruvate carboxylase
PDH complex
A previously normal 2-month-old female presents with jittery spells several hours after meals. She has low blood glucose. Physical exam reveals a liver edge 4 cm below the right costal margin. Percussion of the right chest and abdomen confirms hepatomegaly (enlarged liver).
The infant increases her blood glucose after breast feeding but it is not maintained at normal levels upon fasting. Which of the following is the most likely diagnosis of this patient?
- Fructosemia with inability to liberate sucrose from glucose
- Intestinal malabsorption of lactose
- Glycogen storage disease
- Growth hormone deficiency with inability to maintain glucose
- Galactosemia with inability to convert lactose to glucose
Glycogen storage disease
Which of the following processes generates the most ATP?
- Fatty acid oxidation
- Citric acid cycle
- Glycogenolysis
- Glycolysis
- Pentose phosphate pathway
Fatty acid oxidation
Which of the following characterizes sickle cell disease?
- Binding of BPG to Hgb is diminished
- Arises from a point mutation changing glutamate to lysine on the β-subunit of Hgb
- Expression of the sickled phenotype involves a hydrophilic interaction
- Fetal Hgb (HgbF) is significantly affected
- Aggregation of Hgb tetramers due to a hydrophobic effect
Aggregation of Hgb tetramers due to a hydrophobic effect
A 4-month-old presents with hypoglycemia and hepatomegaly. Injection of glucagon produces no elevation of blood glucose or blood lactate, yet alanine can be converted to glucose. Which of the following liver enzymes would most likely be defective in this patient?
- Glycogen phosphorylase
- Pyruvate kinase
- Pyruvate carboxylase
- Glucose-6-phosphatase
- G6P DH
Glycogen phosphorylase
Which of the following statements explain why fructose 2,6-bisphosphate is important in regulating glycolysis in the liver?
- Is an allosteric inhibitor of phosphofructokinase-1
- Its formation is catalyzed by a glycolytic enzyme
- Has a phosphate group with a high negative free energy of hydrolysis
- Provides an intracellular signal that is sensitive to changes in blood glucose levels
- Is cleaved to triose phosphates in the glycolytic pathway
Provides an intracellular signal that is sensitive to changes in blood glucose levels
Which of the following is an energy-requiring step of glycolysis?
- Hexokinase
- Pyruvate carboxylase
- Phosphoenolpyruvate carboxykinase
- Pyruvate kinase
- Phosphoglycerate kinase
Hexokinase
A middle-Eastern family presents for evaluation because their infant son died in the nursery with severe hemolysis and jaundice. The couple has two prior female infants who are alive and well, and the wife relates that she lost a brother in infancy with severe hemolysis induced after a viral infection.
The physician suspects glucose-6-phosphate dehydrogenase (G6PD) deficiency, implying defective synthesis of which of the following compounds?
- Sucrose and NADPH
- Ribose and NADPH
- Lactose and NADPH
- Deoxyribose and NADP
- Glucose and lactate
Ribose and NADPH
Two patients present, one of whom has a defect in glucose-6-phosphatase and the other exhibits a defect of fructose 1,6-bisphosphatase.
Which of the following is most likely the condition that would only be found in the patient with the defect in glucose-6-phosphatase?
- Glycogen accumulation in the liver
- Lactic acidosis
- Altered muscle metabolism of glucose
- Alanine accumulation in the blood following food deprivation
- Pentose phosphate pathway is not functional
Glycogen accumulation in the liver
The vitamin involved in biochemical reactions concerned with the transfer of methyl, methylene, or formyl groups is a derivative of which of the following vitamins?
- biotin
- pyridoxine
- folic acid
- α-lipoic acid
- ribofavin
folic acid
You are examining the regulatory control of glycolysis by addition of a novel compound to a hepatocyte cell culture system. You discover that addition of the compound results in a decreased rate of ATP production from glucose while simultaneously increasing glucose output into the culture medium.
Further studies demonstrate that the changes observed in your culture system with addition of the compound can be mimicked by altering the cytosolic levels of citrate. Your com- pound is most likely altering the rate of glycolysis by which of the following mechanisms?
- inhibiting 6-phosphofructo-1-kinase (PFK1)
- inhibiting pyruvate kinase
- stimulating PEPCK
- stimulating 6-phosphofructo-1-kinase (PFK1)
inhibiting 6-phosphofructo-1-kinase (PFK1)
A healthy 28-year-old woman exhibits a peak serum glucose concentration of 220 mg/dL within 30 min- of the consumption of 75 g of glucose. Two hours after ingestion, her serum glucose concentration decreases to 100 mg/dL.
The uptake and trapping of glucose within liver cells at high serum glucose concentrations is facilitated by which of the following enzymes?
- phosphofructokinase-1 (PFK1)
- pyruvate dehydrogenase
- glucokinase
- phosphoenolpyruvate carboxykinase (PEPCK)
glucokinase
The Warburg effect states that cancer cells carry out glucose metabolism in a manner distinct from the glycolytic process of cells in normal tissues. Cancer cells tend to “ferment” glucose into lactate even in the presence of sufficient oxygen to support mitochondrial oxidative phosphorylation.
Which of the following enzymes is most responsible for the observations accounting for the Warburg effect?
- glucokinase
- PFK2
- pyruvate kinase
- PFK1
- glyceraldehyde-3-phosphate dehydrogenase
pyruvate kinase
A 27-year-old man complains of intermittent right upper quadrant pain that extends to the inferior tip of his scapula. Analysis of blood reveals mild anemia with the presence of normocytic and normochromic nonsperical erythrocytes. Additional blood work shows elevated levels of glucose 6-phosphate (G6P) and 2,3-bisphosphoglycerate (2,3BPG).
Ultrasonic examination of the abdomen shows cholelithiasis. Following removal of her gallbladder, the stones are examined and shown to contain bilirubin. A deficiency in which of the following enzymes would most explain the signs and symptoms in this patient?
- pyruvate kinase
- PFK1
- pyruvate dehydrogenase
- pyruvate carboxylase
- glucose 6-phosphate dehydrogenase
pyruvate kinase
