Chapter 15: Gene Mutation, DNA Repair, and Transposition

  1. What fluctuates in the fluctuation test of Luria and Delbrück?
    1. The number of resistant cells in different aliquots from the same culture
    2. The probability of a bacterium coming in contact with a phage
    3. The ratio of phages to bacteria (or multiplicity of infection) in the experiment
    4. The number of resistant cells from different independent cultures

  2. A point mutation occurs such that a codon is changed from AGA to AGC. Which term describes this mutation?
    1. Transversion mutation
    2. Insertion mutation
    3. Frameshift mutation
    4. Transition mutation

  3. Which of the following statements about spontaneous mutation rates is false?
    1. The spontaneous mutation rate varies considerably between different organisms.
    2. The spontaneous mutation rate cannot be measured in complex animals such as mammals.
    3. The spontaneous mutation rate is very low for all organisms.
    4. The spontaneous mutation rate varies from gene to gene within an organism.

  4. The role of tautomerism in causing mutations relates to the fact that the process ultimately affects the
    1. Covalent bonding affinities of the nitrogenous base
    2. Hydrogen bonding affinities of the nitrogenous base
    3. Deoxyribose sugar
    4. Ability of DNA to replicate at all

  5. Which of the following statements about deamination is true?
    1. Deamination is induced by nitrous aci
    2. Deamination of cytosine causes a transversion mutation.
    3. Deamination of thymine gives uracil.
    4. Deamination of cytosine gives thymine.

  6. Myotonic dystrophy patients exhibit
    1. No dystrophin and a single nucleotide change
    2. A triplet sequence repeated many times
    3. A single nucleotide change
    4. No dystrophin

  7. Which term describes a mutant E. coli strain that has a nutritional requirement for the vitamin thiamin (vitamin B1)?
    1. Prototroph
    2. Autotroph
    3. Minimal mutant
    4. Auxotroph

  8. The Ames test is used to determine whether or not a compound causes
    1. Chromosome mutations
    2. Gene mutations
    3. DNA repair
    4. Cancer

  9. Which of the following statements about mismatch repair is false?
    1. It determines which base in a mismatch is the incorrect one.
    2. It requires the action of a methylase.
    3. It depends on the fact that parental strand DNA is more heavily methylated.
    4. It recognizes methylated cytosine.

  10. Which of the following statements about photoreactivation repair is true?
    1. It does not occur in eukaryotes.
    2. It requires AP endonuclease.
    3. It requires UV light.
    4. It requires DNA polymerase I.

  11. The discovery of transposons showed that genetic information
    1. Is not fixed in the genome
    2. Can be altered
    3. Is passed from one generation to another
    4. Can be transferred between species

  12. A regulatory mutation has been observed randomly throughout a large population. If the families with members carrying this mutation are not related genetically, this mutation is probably
    1. A neutral mutation
    2. A gametic mutation
    3. A spontaneous somatic mutation
    4. An induced gametic mutation

  13. Why are frameshifts one of the most severe types of mutations?
    1. They occur only in gametes.
    2. More than one gene is affected.
    3. They cannot be reversed.
    4. More than one amino acid, or even entire proteins, are affecte

  14. Base substitutions in a gene may not result in a change in the gene product because
    1. Most DNA is noncoding.
    2. The genetic code is redundant.
    3. The overall structure of the gene product matters more than single bases.
    4. None of the above.

  15. Which of the following statements about a transition mutation in the codon UGG is true?
    1. A transition mutation in the codon UGG could result in a single base substitution to give the new codon CGG.
    2. A transition mutation in the codon UGG could result in a single base substitution to give the new codon AUG.
    3. A transition mutation in the codon UGG would always be silent.
    4. A transition mutation in the codon UGG could result in a single base substitution to give the new codon GGG.

  16. Which mutagenic event does not occur spontaneously?
    1. Deamination
    2. Alkylation
    3. Depurination
    4. Tautomerization

  17. Which of the following events could result in a frameshift mutation?
    1. Tautomeric shift
    2. Point mutation
    3. Base deletion
    4. Incorporation of base analogs

  18. Which enzymes can recognize damaged nucleotide bases?
    1. DNA polymerases
    2. Ligases
    3. AP endonucleases
    4. Glycosylases

  19. Why are liver extracts used in the Ames test?
    1. Liver enzymes activate the bacterial enzymes.
    2. The bacteria require the nutrients present in the liver extract for growth.
    3. Liver enzymes may activate some innocuous compounds, making them mutageni
    4. A liver extract is necessary for the bacteria to produce histidine revertants.

  20. Which bacteria grow on the agar plate if the Ames test is positive?
    1. his– prototrophs
    2. his+ prototrophs
    3. his+ auxotrophs
    4. his– auxotrophs

  21. Which enzyme is responsible for proofreading during replication?
    1. DNA polymerase
    2. RNA polymerase
    3. DNA ligase
    4. DNA glycosylase

  22. Which repair system uses the RecA and LexA proteins?
    1. Mismatch repair
    2. Photoreactivation repair
    3. Proofreading repair
    4. SOS repair