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Home , Thymine

CHE 175 Name______Spring, 2002 ID (SSN)______QUIZ 9 Instructor______

SHORT ANSWER (10 pts each)

1. Explain what a is and show the general structure for a nucleic acid.

2. Shown below are the general structures for the amine bases that account for the diversity of polymers like DNA and RNA. Which one is a and which is a ? N N N N N H N

3. What is the difference between a and a ? 4. Explain why enzymes are necessary to catalyze reactions of with nucleophilic reagents.

5. List two forces that hold together strands of nucleic acids in DNA and RNA.

MULTIPLE CHOICE (5 pts each)

6. Which of the following are known as ? (a) and thymine (c) and thymine (b) and cytosine (d) adenine and guanine

7. Which of the following bases distinguish DNA from RNA? (a) adenine and cytosine (c) guanine and (b) thymine and uracil (d) uracil and adenine

8. Which of the following is the proper name of the nucleoside made from adenine and found in DNA? (a) (b) 2'- (c) 2'-oxyadenosine (d) 2'-deoxyadenine

9. For what compound is ATP an abbreviation? (a) adenine triphosphate (c) (b) adenosine tetraphosphate (d) adenine triphosphoric acid

10. Which of the following statements best explains the source of energy behind ATP? (a) The energy released when a phosphoanhydride bond of ATP is broken. (b) The energy released when adenosine binds to the phosphate. (c) The energy released when ribose binds to the phosphate. (d) The energy released when ATP is reduced. 11. Which of the following reactions converts nucleotide subunits into nucleic acids? (a) Nucleophilic attack on the a -phosphorus of ATP. (b) Nucleophilic attack on the b-phosphorus of ATP. (c) Nucleophilic attack on the g-phosphorus of ATP. (d) None of the above.

12. Which of the following metal ions complexes with cellular ATP to neutralize some of its negative charges at the active site of an enzyme in order that nucleophilic substitution reactions proceed rapidly? (a) iron (b) cobalt (c) magnesium (d) calcium

13. Which of the following constitutes the primary structure of a nucleic acid? (a) The sequence of the bases in the strand. (b) The sequence of riboses in the strand. (c) The sequence of in the strand. (d) The sequence of phosphodiesters in the strand.

14. Which of the following statements is NOT true about the structure of DNA as proposed by Watson and Crick? (a) The number of in DNA is equal to the number of thymines. (b) The number of is equal to the number of . (c) DNA consists of two strands of nucleic acids with the sugar-phosphate backbone on the inside and the bases on the outside. (d) The chains in DNA are held together by hydrogen-bonding.

15. How many hydrogen bonds exist between the cytosine/guanine base pairs? (a) 1 (b) 2 (c) 3 (d) 4

**Bonus (+5 pts) what is your favorite organic reaction?