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
The compound that consists of ribose linked by an N-glycosidic bond to N-9 of adenine is:
- a deoxyribonucleoside.
- a purine nucleotide.
- a pyrimidine nucleotide.
- adenosine monophosphate.
Which one of the following is true of the pentoses found in nucleic acids?
- C-5 and C-1 of the pentose are joined to phosphate groups.
- C-5 of the pentose is joined to a nitrogenous base, and C-1 to a phosphate group.
- The bond that joins nitrogenous bases to pentoses is an O-glycosidic bond.
- The pentoses are always in the β-furanose forms.
- The straight-chain and ring forms undergo constant interconversion.
The phosphodiester bonds that link adjacent nucleotides in both RNA and DNA:
- always link A with T and G with C.
- are susceptible to alkaline hydrolysis.
- are uncharged at neutral pH.
- form between the planar rings of adjacent bases.
- join the 3' hydroxyl of one nucleotide to the 5' hydroxyl of the next.
Based on Chargaff's rules, which of the following are possible base compositions for double-stranded DNA?
- 5%A 45%G 45%C 5%T 0%U
- 20%A 20%G 20%C 20%T 20%U
- 35%A 15%G 35%C 15%T 0%U
- all of the above
- none of the above
In the Watson-Crick structure of DNA, the:
- adenine content of one strand must equal the thymine content of the same strand.
- purine content (fraction of bases that are purines) must be the same in both strands.
- both strands run in the same direction, 3' → 5'; they are parallel.
- the distance between two adjacent bases in one strand is about 3.4 Å.
- phosphate groups project toward the middle of the helix, where they are protected from interaction with water.
The double helix of DNA in the B-form is stabilized by:
- covalent bonds between the 3' end of one strand and the 5' end of the other.
- hydrogen bonding between the phosphate groups of two side-by-side strands.
- hydrogen bonds between the riboses of each strand.
- base-stacking interaction between two adjacent bases in the same strand.
- ribose interactions with the planar base pairs.
Double-stranded regions of RNA:
- are less stable than double-stranded regions of DNA.
- can be observed in the laboratory, but probably have no biological relevance.
- can form between two self-complementary regions of the same single strand of RNA.
- do not occur.
- have the two strands arranged in parallel (unlike those of DNA, which are antiparallel).
When double-stranded DNA is heated at neutral pH, which change does not occur?
- The absorption of ultraviolet (260 nm) light increases.
- The covalent N-glycosidic bond between the base and the pentose breaks.
- The helical structure unwinds.
- The hydrogen bonds between A and T break.
- The viscosity of the solution decreases.
Which of the following deoxyoligonucleotides will hybridize with a DNA containing the sequence (5')AGACTGGTC(3')?
In living cells, nucleotides and their derivatives can serve as:
- carriers of metabolic energy.
- enzyme cofactors.
- intracellular signals.
- precursors for nucleic acid synthesis.
- all of the above.