BIO th December, 2002 FINAL EXAM

Transcription

1 NAME 1 BIO th December, 2002 FINAL EXAM This exam will be taken apart for grading. Please PRINT your name on each page. If you do not have sufficient room for your answer in the space provided, please continue on the back of the page on which the question appears. Question Maximum Points Earned Points I II III IV V VI VII VIII IX X XI XII XIII XIV ================================================================== TOTAL 133 Normalized I II III Score on : Total* = Sum of two best scores + points earned on the Final [COURSE GRADE ON REVERSE SIDE] FINAL NOTE: FULL CREDIT WILL BE GIVEN FOR THOSE ANSWERS WHICH CLEARLY ADDRESS ALL RELEVANT ASPECTS OF THE QUESTIONS IN THE CLEAREST AND MOST CONCISE MANNER.

2 NAME 2 I. [13 Points:1 point for each correct response] Match the metabolic pathways below with the cellular compartments in which they occur. A Cytosol D. Mitochondrial intermembrane space B. Inner mitochondrial membrane E. Endoplasmic reticulum C. Mitochondrial matrix Glycolysis Lactic fermentation Pyruvate dehydrogenation Amino acid degradation Urea cycle Gluconogenesis Cholesterol synthesis Palmitoyl-coA Oxidation Palmitate synthesis Citric acid cycle Oxidative phosphorylation of ADP Pentose phosphate pathway Fatty acid elongation and desaturation II. [8 Points] Answer Either A or B not both. ONLY THE FIRST ANSWER WILL BE GRADED A. How does an increase in blood glucose affect triacylglycerol metabolism in adipocytes? B. You obtain a liver homogenate from a fasting mouse and "spike" it with a high concentration of glucose. In what form would you expect glyogen phosphorylase?

3 NAME 3 III. [8Points] A. During G- protein activation, which subunit exchanges GDP for GTP? What is the intermediate consequence of this exchange? (4 pts) B. Describe the intracellular signaling cascade mediated by phospholipase C activity. How is phospholipase C activated? (4pts) IV. [4 points] List the order in which the following energy sources are used by skeletal muscle to, produce ATP: protein, phosphocreatine, fatty acids, glycogen.

4 NAME 4 V. [12 Points, 1.5 pts each] This question is designed to test your familiarity with heme biosynthesis and catabolism as well as inter tissue cooperation by writing the appropriate item beside each description. A. Principal site of red blood cell production in adult humans B. In mature red blood cell, aerobic; makes globin, heme and purine nucleotides C. Involved in transport of billirubin from the spleen to the liver D. Degrades worn out red blood cells, part of the reticuloendothelial system. E. Required for removal of glucuronic acid residues from billirubin diglucuronide. F. Light-sensitive heme precursor that accumulates when urogen III cosynthase is defective. G. Storage form of iron in the bone marrow tissue. H. Principal site of feedback regulation of heme synthesis. VI. [8 points] 1. Malonic acid is a structural analog of succinic acid. Addition of malonate to a suspension of respiring, intact mitochondria is followed by a rapid cessation of O 2 consumption. Explain; the correct answer is short but you must be specific. (4pts) 2. Short of removing the malonate, how might you restore respiration and coupled phosphorylation? Your assumptions and rationale must be explicitly stated. [Note: Conversion of the malonate to malonyl-scoa is not an acceptable option.] Explain. (4pts)

5 NAME 5 VII. [10 points] A. Answer Either A or B not both. ONLY THE FIRST ANSWER WILL BE GRADED A sample of liver tissue was obtained post mortem from the body of a person believed to be genetically deficient in one of the enzymes of carbohydrate metabolism. A homogenate of the liver sample had the following characteristics. 1) It degraded glycogen to produce G-6-P. 2) It did not synthesize glycogen from any sugar, nor did it utilize galactose as an energy source. 3) It synthesized G-6-P from lactate. Which of the following enzymes was deficient? Give specific reasons for your answer. You must also state specifically the basis for elimination of two choices. 1) glycogen phosphorylase 2) fructose-1,6-phosphatase 3) UDP-glucose pyrophosphorylase B. A weight-reducing diet heavily promoted several years ago required the daily intake of "liquid protein" (soup of hydrolyzed gelatin; a collagen product), water and an assortment of vitamins. All other food and drink were to be avoided. People on this diet typically lost lb. in the first week. A number of people on this diet died. What are some of the dangers inherent in the diet and how can they lead to death? [Hint: It is not acceptable to invoke contamination or experimental artifacts. Consider ammonia toxicity and why this is likely in this case, as well as the composition of collagen.]

6 NAME 6 VIII. [ 12 points; 1 pt each] For each description (below) select the ONE most appropriate vitamin; there are two parts for which there are two possibilities you are to provide either of them. 1. Required for oxidative decarboxylation of "-keto acids 2. Its synthesis is inhibited by sulfanilamide 3. Participates in the conversions involving free radicals 4. Participates in 1C transfers at the level of a formyl group 5. Participates in 1C transfers at the level of a carboxyl group 6. Participates in hydride ion transfers 7. Participates in the transfer of two hydrogen atom transfers, each with one electron 8. Participates in postranslational hydroxylation 9. A derivative of cholesterol 10. The precursor for FMN 11. Contains a thiazoline ring 12. Contains a redox active disulfide A. Biotin B. Vitamin B 12 C. Ascorbic acid D. Thiamine E. Riboflavin F. Folic acid G. Vitamin A H. Vitamin D I. Vitamin K J. Vitamin E K. Niacin L. Lipoic acid

7 NAME 7 IX. [7 points] For each of the following, choose the ONE best answer A. Hormonal stimulation of the second messenger inositol 1,4,5-triphosphate [IP 3 ] quickly leads to the release of which intracellular second messenger? a. cgmp b. camp c. prostaglandin d. calcium e. leukotriene B. A strong cup of coffee would be expected to a. interfere with the synthesis of prostaglandins b. decrease the effects of glucagon c. enhance the effects of epinephrine d. provide the vitamin niacin e. none of the above C. During starvation, ketone bodies are synthesized in a. adipose tissues b. brain c. liver d. muscles e. thymus D. After an injection of insulin in a diabetic patient with hyperglycemia, there is a prompt normalization of plasma glucose, due to the recruitment of which of the following transport proteins to the plasma membrane? a. GLUT 1 b. GLUT 2 c. GLUT 3 d. GLUT 4 e. GLUT 5 E. Glycolysis is the only ATP-producing pathway in a. erythrocytes b. lymphocytes c. reticulocytes d. hepatocytes e. neurons f. adipocytes F. In the normal resting state of humans, most of the blood glucose burned as fuel is consumed by a. the liver b. the brain c. the kidneys d. adipose tissue e. muscle

8 NAME 8 G. Elevation of cytosolic calcium from intracellular stores can be caused by a. camp b. cgmp c. ccdp d. inositol 1,4,5-triphosphate [IP 3 ] e. diacylglycerol

9 NAME 9 X. [16 points] This question is presented in the form of a crossword puzzle. It is designed to test your familiarity with terms and concepts associated purine nucleotide metabolism. As with most crossword puzzles, following the clues is a parenthetical expression which indicates the number of letters/numbers required for a particular answer; where answers are to be given in terms of abbreviations this is also indicated. You cannot possibly solve the entire puzzle in the time allotted; therefore, choose only 8 items. It is important, as with most crossword puzzles, that the answers are spelled properly. If you enter an answer and later decide that the answer is wrong cross it out or erase it. Only your first 8 answers will be graded. It is essential that you write legibly. Full credit will be awarded for correct, complete, legible, correctly-spelled answers. 2 points will be awarded for each correct answer therefore total credit for this question is 16 points.

10 NAME 10

11 NAME 11

12 NAME 12 XI. [10 Points] Identify ONE specific example of a genetic defect in metabolism that have been considered in class or in the text, and for which the biochemical basis is clear. You must describe BOTH the biochemical basis of the lesion as well as the metabolic/physiological consequences of the defect in as much detail as you are able.

13 NAME 13 XII. [10 points] A. Describe the biochemical and cellular processes that are involved in glucose stimulated insulin secretion (GSIS). (5pts) B. K m k CAT Normal 8.4mM 54.4moles.mole!1.sec!1 Mutant (Val455Met) 2.9mM 50.2 " " " " The table above provides values for relevant kinetic parameters for glucokinase from $- cells from normal individuals and patients having a mutation at residue 455 of the polypeptide. Keeping the normal processes involved in GSIS in mind, what would the effect of this mutation be on levels of insulin and glucose in the blood? Explain your rationale in as much detail as you are able. (5pts)

14 NAME 14 XIII. [8 points] Consider the situation where you want to check if two proteins A and B have a direct interaction using fluorescence resonance energy transfer (FRET) technique. You have options to use any of the fluorophores provided in the table. Which pair would you use and why? Florophores Absorption Emission wavelength (nm) wavelength (nm) Alexa Bodipy 564/ ECFP Cy FITC EYFP GFP XIV. [7 Points] a) Why is X-ray crystallography important? (2 pts) b) What steps do you experimentally take to generate a 3D structure? ( 3pts) c) Which step is the most limiting and why? (2 pts)

15 NAME 15