(65 pts.) 27. (10 pts.) 28. (15 pts.) 29. (10 pts.) TOTAL (100 points) Moorpark College Chemistry 11 Spring Instructor: Professor Gopal

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1 Moorpark College Chemistry 11 Spring 2012 Instructor: Professor Gopal Examination # 5: Section Five May 1, 2012 Name: (print) GOOD LUCK! Directions: Make sure your examination contains TWELVE total pages (including this cover sheet and the amino acids structure page on the back) when instructed to do so. Answer all the questions in the spaces provided. Question (65 pts.) 27. (10 pts.) 28. (15 pts.) 29. (10 pts.) TOTAL (100 points) Points 1

2 Chemistry 11 Spring 2012 Examination #5 For the first portion of this exam, select the best answer choice for the questions below and mark the answers on your scantron. Then answer the free response questions that follow (100 pts. total; multiple choice 2.5 pts. each). For questions 1-4, match the carbohydrate with its size/functional group/description: A. polysaccharide B. monosaccharide, aldohexose C. disaccharide D. monosaccharide, ketohexose 1. lactose 2. glycogen 3. D-glucose 4. D-fructose 5. The order of amino acids in a peptide or protein I. is critical to its structure and function II. determines the primary structure of a protein III. is critical to neither structure nor function A. Only I is true. B. Only II is true. C. Only III is true. D. Both I and II are true E. Both II and III are true. 6. Soap is formed from: A. Two hydrophobic compounds B. a physical change when fats are heated C. Two hydrophilic compounds D. oils or fats by reacting them with an base E. oils or fats by reacting them with an acid 2

3 7. When sucrose is converted to glucose and fructose A. it gives a negative test with Fehlings reagent B. a molecule of water is added to sucrose C. a molecule of water is removed from sucrose D. a monosaccharide is converted to two disaccharides E. an acetal is formed 8. At physiological p, the NET charge on an amino acid with no ionizable side chain is A. +1 B. 0 C. +2 D. -1 E Fatty acids with a low melting point tend to be? A. unsaturated B. solid at room temperature C. long chain hydrocarbons D. hydrogenated E. saturated 10. As a result of mutarotation, D-glucose exists in all of the following forms EXCEPT: A. L-glucopyranose B. β-anomer C. free aldehyde D. α-anomer E. all are true 11. The dipeptides trp-val and val-trp are A. cis-trans isomers B. conformational isomers C. constitutional isomers D. configurational isomers E. they are the same 3

4 12. This transport carrier enables fat and cholesterol to travel through the blood A. glycerol B. micelle C. bile D. triglyceride E. lipoprotein 13. The formation of cyclic structures in sugars with creation of an additional chiral centre results from an alcohol reacting with a(n): A. secondary alcohol B. phosphate group C. carboxylic acid group D. aldehyde or ketone E. primary alcohol 14. All of the following are true of protein denaturation except that it A. does not alter the tertiary structure of a protein B. it does not affect the primary structure of proteins C. may be caused by a p change D. could result from a temperature change E. hard boiled egg is an example of a denatured protein 15. In the formation of a larger molecule like a disaccharide, what type of reaction would join two smaller molecules together? A. hydrophobic reaction B. hydrolysis reaction C. dehydration reaction D. denaturation reaction E. hydrophilic reaction 16. Trans fats lower A. DL cholesterol B. LDL cholesterol C. Shelf life of lipids D. eart disease E. None of the above 4

5 17. An anomeric carbon is A. stereocentric B. participates in the formation of a glycosidic bond C. a carbon that lies between the two oxygen atoms of the formed hemiacetal or acetal group D. involved in forming α-d-glucose and β-d-glucose structures E. all of the above are true 18. Which of the information regarding proteins is INCORRECT? A. Proteins are made up of hydrophobic and hydrophilic amino acids. B. There are two achiral amino acids. C. There are two amino acids that have more than one chiral carbon. D. The side chains of amino acids contribute a large extent in determining the properties of a protein. E. All the information above regarding proteins is correct. 19. A high LDL level combined with a low DL level may lead to everything EXCEPT A. atherosclerosis B. faulty cholesterol transport C. high blood pressure D. kidney dysfunction E. transport of cholesterol from plaques deposited in the arteries to the liver 20. Starch is a carbohydrate A. that is made up of glucose units B. has a hemiacetal group at one end C. tests negative with Fehling s reagent and positive with iodine D. is a storage form of sugar in plants E. all of the above 21. The interaction that forms between the nonpolar side chains of amino acids is called A. salt bridges B. hydrogen bonds C. hydrophobic interaction D. alpha helix E. disulfide bridges 5

6 22. Which of the following about lipids is TRUE? A. Lipids are not soluble in liquid ammonia B. Lipids are soluble in CCl 4 C. Lipids form an integral part of the cell membrane D. Lipids store energy within fat cells E. All of the above are true. 23. What kind of noncovalent interaction occurs between the side chains of serine and glutamine? A. disulfide bond B. metal ion coordination C. salt bridge D. hydrogen bonding E. hydrophobic interaction 24. Which of the following facts about cholesterol is TRUE? A. Cholesterol is a lipoprotein B. Cholesterol is readily soluble in water. C. Cholesterol has a fused five-ring structure. D. Cholesterol is used to make soap. E. Cholesterol serves as a starting material for the synthesis of other steroids. 25. Reaction of glucose with NaB 4 / 2 O or hydrogen/pd A. reduces the aldehyde group on glucose to an alcohol B. reduces the aldehyde group on glucose to a carboxylic acid C. reduces the aldehyde group on glucose to a ketone D. oxidizes the aldehyde group on glucose to a carboxylic acid E. converts the alcohol group on glucose to an alkene 26. Which of the following is TRUE of the spacial distribution of the hydroxyl groups in β- D-glucopyranose? A. They are all in axial positions. B. They are all in equatorial positions. C. The hydroxyl on carbon-1 is axial; those remaining are equatorial. D. The hydroxyl on carbon-1 is equatorial; those remaining are axial. E. They have equal but opposite optical rotations. END OF MULTIPLE COICE 6

7 27. (10 pts. total). This section involves a series of questions dealing with amino acids and proteins. A. (4 points) What are the two common secondary structures in proteins and how do they differ from one another? Show using a diagram and indicate the type of bond formation clearly. 7

8 B. Gamma-carboxyglutamic acid is used to build certain proteins that play a role in blood clotting. O O C O C O Gamma-carboxyglutamic acid 2 N 1. (3 points) Identify the side chain in this amino acid and enclose it in a box. Classify the amino acid as hydrophobic or hydrophilic. If it is hydrophilic, classify it as acidic, basic, or neutral. 2. (2 points) Draw the structure of the amino acid as it will appear at p (1 pt.) Are there any chiral carbon atoms in this molecule? If so, which ones are they? Circle the chiral carbon(s) in the structure above. 8

9 28. (15 points). The ratio of infants born with a genetic defect called galactosemia is 1:18,000. In this condition, galactose accumulates in the blood and in the urine and this buildup of galactose leads to several health problems. A. (2 points) What is the disaccharide which on hydrolysis leads to the buildup of galactose in infants who do not have an enzyme to metabolize galactose? B. (2 points) Besides galactose, what is the other product of hydrolysis of this disaccharide? C. (5 points) Draw the aworth projection of the disaccharide given the Fischer projection of galactose below: 9

10 D. (3 points) Is this disaccharide a reducing or non-reducing sugar? Why? E. ( 3 points) Describe a test you did in the lab to determine if a sugar is reducing or non-reducing. You should mention all key points to get full credit. 29. LAST SECTION! LIPIDS (10 points total) A. (3 points) What is the difference between a fat and fatty acid? B. (2 points) What is the other name for a fat molecule? Name the functional group present in this molecule. C. Answer the questions regarding the molecule below: 1. Write the molecular formula of the saturated fatty acid portion of this molecule? (1 pt.) 10

11 2. Are the unsaturated fatty acid components of this molecule cis or trans isomers? (1 pt.) 3. Write the reaction of the molecule above with a strong base? What is this reaction called? (3 pts.) 11

12 ydrophobic nonacidic side chains 3 N Glycine Gly, G 3 C 3 N Alanine Ala, A 3 N Valine Val, V 3 N Leucine Leu, L 3 N Isoleucine Ile, I N 2 Proline Pro, P N 3 N Tryptophan Trp, W 3 N Phenylalanine Phe, F 3 CS 2 C 2 C 3 N Methionine Met, M ydrophobic acidic side chains 3 N ydrophilic nonacidic side chains O 3 N 3 N ydrophilic acidic side chains O 2 C 3 N Serine Ser, S S Aspartic acid Asp, D O Threonine Thr, T O 2 C Cysteine Cys, C 3 N Se 3 N O 2 N 3 N Asparagine Asn, N Glutamic acid Glu, Q Selenocysteine Sec, U O 2 N 3 N O 3 N Glutamine Gln, Q Tyrosine Tyr, Y 2 N ydrophilic basic side chains 3 N 2 N N N 3 N N N 3 N Lysine Lys, K Arginine Arg, R istidine is, 12