Chem 471 | Problem Set 8 | Preview

Chapter 8 Nucleotides and Nucleic Acids
Multiple Choice Questions. Choose one best answer.
Due Wed 7 Apr 2010 on Blackboard

  1. The compound that consists of ribose linked by an N-glycosidic bond to N-9 of adenine is:

    1. a deoxyribonucleoside.
    2. a purine nucleotide.
    3. a pyrimidine nucleotide.
    4. adenosine monophosphate.
    5. adenosine.

  2. Which one of the following is true of the pentoses found in nucleic acids?

    1. C-5 and C-1 of the pentose are joined to phosphate groups.
    2. C-5 of the pentose is joined to a nitrogenous base, and C-1 to a phosphate group.
    3. The bond that joins nitrogenous bases to pentoses is an O-glycosidic bond.
    4. The pentoses are always in the β-furanose forms.
    5. The straight-chain and ring forms undergo constant interconversion.

  3. The phosphodiester bonds that link adjacent nucleotides in both RNA and DNA:

    1. always link A with T and G with C.
    2. are susceptible to alkaline hydrolysis.
    3. are uncharged at neutral pH.
    4. form between the planar rings of adjacent bases.
    5. join the 3' hydroxyl of one nucleotide to the 5' hydroxyl of the next.

  4. Based on Chargaff's rules, which of the following are possible base compositions for double-stranded DNA?

    1. 5%A 45%G 45%C 5%T 0%U
    2. 20%A 20%G 20%C 20%T 20%U
    3. 35%A 15%G 35%C 15%T 0%U
    4. all of the above
    5. none of the above

  5. In the Watson-Crick structure of DNA, the:

    1. adenine content of one strand must equal the thymine content of the same strand.
    2. purine content (fraction of bases that are purines) must be the same in both strands.
    3. both strands run in the same direction, 3' → 5'; they are parallel.
    4. the distance between two adjacent bases in one strand is about 3.4 Å.
    5. phosphate groups project toward the middle of the helix, where they are protected from interaction with water.

  6. The double helix of DNA in the B-form is stabilized by:

    1. covalent bonds between the 3' end of one strand and the 5' end of the other.
    2. hydrogen bonding between the phosphate groups of two side-by-side strands.
    3. hydrogen bonds between the riboses of each strand.
    4. base-stacking interaction between two adjacent bases in the same strand.
    5. ribose interactions with the planar base pairs.

  7. Double-stranded regions of RNA:

    1. are less stable than double-stranded regions of DNA.
    2. can be observed in the laboratory, but probably have no biological relevance.
    3. can form between two self-complementary regions of the same single strand of RNA.
    4. do not occur.
    5. have the two strands arranged in parallel (unlike those of DNA, which are antiparallel).

  8. When double-stranded DNA is heated at neutral pH, which change does not occur?

    1. The absorption of ultraviolet (260 nm) light increases.
    2. The covalent N-glycosidic bond between the base and the pentose breaks.
    3. The helical structure unwinds.
    4. The hydrogen bonds between A and T break.
    5. The viscosity of the solution decreases.

  9. Which of the following deoxyoligonucleotides will hybridize with a DNA containing the sequence (5')AGACTGGTC(3')?

    1. (5')CTCATTGAG(3')
    2. (5')GACCAGTCT(3')
    3. (5')GAGTCAACT(3')
    4. (5')TCTGACCAG(3')
    5. (5')TCTGGATCT(3')

  10. In living cells, nucleotides and their derivatives can serve as:

    1. carriers of metabolic energy.
    2. enzyme cofactors.
    3. intracellular signals.
    4. precursors for nucleic acid synthesis.
    5. all of the above.