Questions:

1. All of the following statements about the pentose phosphate pathway are true EXCEPT
  1. Its two functions are to produce NADPH and ribose-5-P
  2. It uses glucose-6-P as a substrate when producing NADPH and CO2
  3. Glucose-6-phosphate dehydrogenase is the control enzyme and it is regulated by the NADPH concentration of the cell
  4. If it is producing more than twice as much NADPH as ribose-5-P, it can produce glyceraldehyde-3-P and fructose-6-P
  5. It is found in the mitochondria of liver, muscle and brain but is absent from most other tissues of the body
2. If a cell only needs to synthesize ribose-5-P and not NADPH, the enzymes of the hexose monophosphate shunt would use the following substrates from glycolysis
  1. Fructose-6-phosphate and NADPH
  2. 3-Phosphoglycerate and fructose-6-phosphate
  3. Glyceraldehyde-3-phosphate and fructose-6-phosphate
  4. Glucose-1-phosphate and lactate
  5. Reduced glutathione and glutathione peroxidase
3. NADPH is used by most cells as
  1. A substrate for the electron transport chain
  2. To produce ribose-5-P from glyceraldehyde-3-P and fructose-6-P
  3. A reducing agent in detoxification reactions
  4. An oxidizing agent in reductive biosynthesis
  5. A substrate for transketolase reactions
4. You have a patient that has hemolytic anemia as a result of eating fava beans.  She would have a deficiency of the enzyme ______________ and would not be able to synthesize enough _____________________________
  1. Glucose-6-P dehydrogenase;           ribose-5-P and ribulose-5-P
  2. Glucose-6-P dehydrogenase;            oxidized glutathione and HOOH
  3. Glucose-6-P dehydrogenase;            NADPH
  4. 6-Phosphogluconate dehydrogenase;   reduced glutathione + HOOH
  5. 6-Phosphogluconate dehydrogenase;   NADH and 3-phosphoglycerate
5. Your patient, Al Martini, has glucose-6-phosphate dehydrogenase deficiency as a result of taking a sulfa drug.  He has never been diagnosed with this disease before.  He suffers from hemolysis while his white blood cells look OK. You feel certain that the following statements are true EXCEPT
  1. He has a fairly common genetic disease
  2. This is probably the first time his system has been challenged with a lot of free radicals (reactive oxygen species)
  3. He has some glucose-6-phosphate dehydrogenase activity but less than most people
  4. Most cells were not lysed because those cells had other ways to produce NADPH
  5. His red blood cells have no trouble making reduced glutathione but cannot oxidize it
6. Which of following statements is NOT true? If a cell needs to make ribose-5-phosphate but the concentration of NADPH is very high, the cell will
  1. use the 6-phosphogluconate dehydrogenase reaction
  2. use the nonoxidative portion f the Pentose Phosphate Pathway
  3. use the nonoxidative portion of the hexose monophosphate shunt
  4. make ribose-5-phosphate using fructose-6-phosphate and glyceraldehyde
  5. make ribose-5-phosphate from glycolytic intermediates
7. NADPH is used as a substrate for all of the following EXCEPT
  1. Malate dehydrogenase
  2. Glutathione reductase
  3. Fatty acid synthesis
  4. Cytochrome P450 monooxygenases
  5. Deoxynucleotide synthesis
8. All of the following enzymes and metabolites are found in the pathway for the reduction of HOOH except
  1. 6-phosphogluconate dehydrogenase
  2. NADH + H+
  3. Glutathione reductase
  4. Reduced glutathione
  5. Glutathione peroxidase

Answers:

1. Answer: E. Chapter 29 , Objective 1: Describe the pentose phosphate pathway; Names: Functions: Substrates: Product: Control Enzymes: Regulation: Compartment(s): Tissues of interest: Back to question 1.
2. Answer: C. Chapter 29 , Objective 2: If a cell needs both NADPH and ribose-5-phosphate, what substrates from glycolysis are used by the pentose phosphate pathway to make them? If a cell needs only ribose-5-phosphate what substrates from glycolysis are used by the pentose phosphate pathway? Back to question 2.
3. Answer: C. Chapter 29 , Objective 3: What is NADPH used for? Back to question 3.
4. Answer: C. Chapter 29 , Objective 4: Assume that you have a patient that has hemolytic anemia a result of eating fava beans. Name the deficient enzyme and the other enzymes and products in the pathway that leads to the reduction of HOOH. Back to question 4.
5. Answer: E. Chapter 29, Objective 5: Concerning Al Martini: This patient has glucose-6-phosphate dehydrogenase deficiency. Why are red blood cells lysed while other cells of the body remain intact? Why didn't this disease show up earlier in life? Back to question 5.
6. Answer: A. Chapter 29, Objective 2: If a cell needs both NADPH and ribose-5-phosphate, what substrates from glycolysis are used by the pentose phosphate pathway to make them? If a cell needs only ribose-5-phosphate what substrates from glycolysis are used by the pentose phosphate pathway? Back to question 6.
7. Answer: A. Chapter 29, Objective 3: What is NADPH used for? Back to question 7.
8. Answer: B. Chapter 29, Objective 4: Assume that you have a patient that has hemolytic anemia a result of eating fava beans. Name the deficient enzyme and the other enzymes and products in the pathway that leads to the reduction of HOOH. Back to question 8.