Practice Chem 103.3 FINAL EXAM

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Chemistry 103.3 – Spring 2022 Final Exam - May 20, 2022 Name: (print)___________________________________ Part 1: Circle the best answer for each question. 2 pts each (50 points) 1. A glucogenic amino acid may feed its carbon skeleton into each intermediate pool listed below EXCEPT: A. Malate B. Succinate C. a -Ketoglutarate D. Acetyl-CoA E. Fumarate 2. Which of the following molecules carries an amino group from the tissues to the liver? A. Fructose B. Chylomicrons C. Ketone bodies D. Glutamine E. Lactate 3. Which pathway listed below operates in liver but not in muscle? A. Glycolysis B. Glycogen breakdown C. Glycogen synthesis D. Gluconeogenesis with release of free glucose E. Insulin-stimulated pathways 4. When blood glucose is abnormally low, the pancreas releases: A. Epinephrine B. Insulin C. Thyroxin D. Glucagon E. Cholesterol 5. Which statement below about fatty acid degradation is false ? A. It involves cycles of cleaving a 2-carbon fragment from the carboxyl end (the b -carbon). B. It takes place in the mitochondrial matrix. C. ATP is required to convert each FA to a CoA derivative. D. Each cycle requires 2 NAD+ molecules. E. Each fatty acid is initially converted to a carnitine derivative. 1

6. Which statement about the Citric Acid Cycle is false ? A. One 6C molecule is converted to a 4C molecule B. Oxidative decarboxylation occurs twice C. The cycle is activated by an increase in [AMP] D. Ketogenic amino acids feed into the a -ketoglutarate pool. E. High levels of ATP suppresses the activity of the Cycle 7. Fructose-2,6-bisphosphate is A. An activator of PFK-1 B. Depleted by the downstream effects of glucagon C. An activator of glycogen breakdown D. An inhibitor of the Citric Acid Cycle E. An intermediate of the glycolytic pathway 8. The structure of urea is H 2 N-C(=O)-NH 2. Which statement below about the Urea Cycle is FALSE ? A. It occurs entirely in the mitochondrial matrix. B. Arginine can be synthesized by this pathway. C. Fumarate is a product of the pathway. D. NH 4 + donates one of the amino groups of urea. E. Aspartate donates one of the amino groups of urea. 9. The first 5 reactions of glycolysis are referred to as the "energy investment" portion of the process because these steps A. consume ATP instead of producing it B. generate waste products which cost ATP for disposal C. produce NADH which is less energy-rich than ATP D. involve several endergonic isomerizations E. none of the above 10. In contrast to transamination, deamination of an amino acid results in A. a new amino acid B. free NH 4 + C. glutamine D. transfer of amino group to another molecule 11. One of the enzymes involved in glycolysis is phosphofructokinase. What type of biochemical reaction does it catalyze? A. Transfer of a carbonyl group from glucose to fructose. B. Removal of a phosphate group from fructose-6-phosphate. C. Transfer of a phosphate group from ATP to fructose-6-phosphate. D. Transfer of a phosphate group from fructose-1,6-bisphosphate to fructose. E. None of the above 2

12. One round of fatty acid synthesis results in A. consumption of 2 NADH/H+ B. consumption of 2 FADH 2 C. release of 1 NADH/H+ and 1 ATP D. consumption of 2 NADPH/H+ E. release of 2 NADPH/H+ 13. The major site of formation of acetoacetate from fatty acids is the: A. adipose tissue B. intestinal mucosa C. muscle D. liver E. kidney 14. Which intermediate of the Citric Acid Cycle can be increased by direct transamination of ASP? A. fumarate B. isocitrate C. succinate D. oxaloacetate E. citrate 15. Of the glycolytic enzymes given below, which one can be regulated by phosphorylation by PKA? A. aldolase B. glyceraldehyde-3-P dehydrogenase C. pyruvate kinase D. phosphoglycerate kinase E. hexokinase 16. Which statement about Acetyl-CoA carboxylase is false ? A. it is the key regulatory step of the fatty acid synthesis pathway B. it is activated by phosphorylation by PKA C. it can be found in the cytoplasm D. the reaction requires CO 2 E. it is activated by insulin action 17. NADH produced by glycolysis under anaerobic conditions will be re-oxidized in the cytosol by which of the following enzymes so that glycolysis continues? A. succinate dehydrogenase B. glyceraldehyde-3-P dehydrogenase C. lactate dehydrogenase D. a -ketoglutarate dehydrogenase E. substrate-level phosphorylation 3

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18. Glycogen breakdown is A. inactivated by phosphorylation B. activated when glycogen synthesis is activated C. activated by insulin D. present in red blood cells E. performed by glycogen phosphorylase 19. Of the molecules listed below, which one cannot be made into pyruvate? A. lactate B. oxaloacetate C. PEP D. alanine E. leucine 20. An elevated insulin level in the blood: A. Inhibits glucose uptake by the liver. B. Inhibits glycogen synthesis in the liver and muscle. C. Results from a sub-normal blood glucose level. D. Stimulates fatty acid breakdown. E. Stimulates synthesis of fatty acids and triacylglycerols. 21. Enzymes that are affected by the binding of an activator are called A. zymogens B. allosteric enzymes C. proenzymes D. induced enzymes E. phospho-dephospho regulated enzymes 22. What is the role of a chylomicron? A. to transport triacylglycerols in the bloodstream B. to synthesize cholesterol and other steroids C. to move triacylglycerol across the cell membrane D. to store excess triacylglycerols until they are needed E. to transport acetyl-CoA from the cytosol to the mitochondria 23. When epinephrine interacts with a cell, the step immediately following activation of adenylate cyclase is: A. conversion of cyclic AMP to AMP B. activation of a G protein in the cell membrane C. activation of phosphodiesterase D. conversion of ATP to cyclic AMP 4

24. If an amino acid has pK 1 = 2 and pK 2 = 9, then its isoelectric point (pI) is A. 2 B. 6 C. 3.5 D. 11 25. Name the peptide below using the three-letter code for each amino acid residue. A. ALA-PHE-ILE B. ALA-PHE-LEU C. SER-PHE-VAL D. SER-TYR-LEU Part 2: Fill in the blanks. 2 points per response. (32 points) 26. Match the hormone with the physiological state: A. Glucagon ___ Fight or Flight B. Epinephrine ___ Fed state C. Insulin ___ Fasted state 27. Match the key regulatory enzyme with the pathway that it regulates. A. Acetyl-CoA carboxylase ___ glycogen breakdown B. Glycogen phosphorylase ___ glycolysis C. Isocitrate dehydrogenase ___ citric acid cycle D. Phosphofructokinase-1 ___ fatty acid synthesis 28. What is the effect of insulin on the following pathways in muscle? Indicate increases or decreases . A. Fatty acid synthesis ____________________ B. Glycogen breakdown ___________________ C. Glycogen synthesis _____________________ 29. Match each item on the left with the best descriptor on the right. Each descriptor can be used only once. A. a saturated C16 fatty acid ___ linoleic acid B. a C18 fatty acid with 1 double bond ___ palmitic acid C. a C18 fatty acid with 2 double bonds ___ stearic acid D. a saturated C18 fatty acid ___ linolenic acid E. a C18 fatty acid with 3 double bonds ___ oleic acid 5

30. Caffeine inhibits phosphodiesterase, the enzyme that degrades cAMP. When a runner consumes a cup of coffee just before a marathon, what happens to their liver glycogen? Indicate increases or decreases . ________________. Part 3: Fill in the blanks. 1 point each. (18 points) 1. A bond connecting the two glucose units in maltose is a(an)____________________ linkage. 2. Pyridoxal-phosphate is the cofactor for ________________ enzymes. 3. When ATP is produced by direct transfer of a phosphate group rather than a proton gradient, the process is referred to as ___________________ phosphorylation. 4. Each oxidation during fatty acid catabolism directly produces one molecule of ______________________ and the fatty acid molecule has been shortened by ____ carbon atom(s). 5. If lipid catabolism produces more acetyl-CoA than the citric acid cycle can consume, but there is still a need for energy, acetyl-CoA molecules condense to form _______________ . 6. Digestion of lipids begins in the __________________ by enzymes called _______________. 7. The pro-enzyme for trypsin is called __________________. 8. Name one glycerophospholipid that is commonly found in membranes: ________________. 9. Fatty acid synthesis produces a product with ____ carbons. 10. Name a tissue that can release free glucose into the blood upon demand: ______________. 11. During fatty acid synthesis, chemical steps involve reduction or oxidation? _____________. 12. During a fast, the first stored fuel to be used by the body is __________________, followed by use of ________________. 13. Which part of a triacylglyceride can be converted to glucose? _________________. 14. Glycerophospholipids are built on a backbone of _______________, whereas sphingolipids are built on a backbone of ________________. 6

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