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| 1 | |
The nucleotide change ________ is an example of a transversion, while the nucleotide change ________ is an example of a transition. |
| | A) | A→G; C→G |
| | B) | C→G; A→G |
| | C) | T→C; A→G |
| | D) | C→T; G→A |
| | E) | G→C; C→G |
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| 2 | |
Which type of mutation is most likely to revert?
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| | A) | deletion |
| | B) | translocation |
| | C) | inversion |
| | D) | transposition |
| | E) | transition |
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| 3 | |
Which type of mutation is least likely to revert?
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| | A) | deletion |
| | B) | translocation |
| | C) | inversion |
| | D) | transposition |
| | E) | transition |
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| 4 | |
The hydrolysis of an -NH2 group from a base is called ________, while intercalating agents such as acridine orange function as mutagens by causing ________:
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| | A) | deamination; transversions |
| | B) | deamination; deletions or insertions |
| | C) | excision repair; deletions or insertions |
| | D) | excision repair; transversions |
| | E) | deletion; transitions |
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| 5 | |
The fluctuation test of Luria and Delbruck established that:
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| | A) | Bacterial resistance to phages and other bactericides is the result of mutations. |
| | B) | Mutations arise as a directed response to environmental change. |
| | C) | Mutations occur spontaneously as a result of random processes that can happen at any time and anywhere in the genome. |
| | D) | In E. coli, the number of mutants per tube was relatively constant. |
| | E) | a and c |
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| 6 | |
Mutations that reduce the function encoded by the wild-type allele are known as ________, while mutations that eliminate all function are known as ________:
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| | A) | null mutations; neomorphic mutations |
| | B) | hypomorphic mutations; null mutations |
| | C) | hypermorphic mutations; hypomorphic mutations |
| | D) | conditional mutations; null mutations |
| | E) | neomorphic mutations; null mutations |
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| 7 | |
A conditional bacterial mutant is unable to methylate DNA at higher temperatures. What happens when you shift bacteria to these higher temperatures?
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| | A) | the new DNA strand is more likely to contain errors |
| | B) | the older DNA strand is more likely to contain errors |
| | C) | the rate of mutation goes up |
| | D) | a and c |
| | E) | b and c |
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| 8 | |
Duplication of multiple three-nucleotide repeats is responsible for:
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| | A) | sickle-cell anemia |
| | B) | xeroderma pigmentosum |
| | C) | alkaptonuria |
| | D) | trisomy 21 |
| | E) | fragile X syndrome |
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| 9 | |
Which of the following are parts of the Ames test for mutagenicity?
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| | A) | auxotrophic bacteria are converted to prototrophs that survive. |
| | B) | prototrophic bacteria are converted to auxotrophs that survive. |
| | C) | cells are treated with no mutagen and only those with mutations survive. |
| | D) | a and b |
| | E) | a and c |
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| 10 | |
In an Ames test for mutagenicity, rat liver enzymes are accidentally excluded from the compound under test. What can you say about the results?
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| | A) | the mutation rate will probably rise |
| | B) | the mutation rate will probably decline |
| | C) | the results are less relevant to mammals |
| | D) | the results are less relevant to bacteria |
| | E) | no mutations will form |
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| 11 | |
Assume that a new antidepressant is developed. The structure is novel and is tested using the Ames test for mutagenicity. The following results are obtained:
| | Sample | Number of his+
revertant colonies |
| | distilled water | 2 | | distilled water + rat liver enzymes | 3 | | antidepressant | 37 | | antidepressant + rat liver enzymes | 39 |
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What conclusion is most consistent with these data?
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| | A) | the drug and its conversion products are not mutagenic. |
| | B) | rat liver enzymes are mutagenic. |
| | C) | the drug is not mutagenic but can be converted into strong mutagens. |
| | D) | the drug is mutagenic and can be converted into strong mutagens. |
| | E) | the drug and its conversion products are equally mutagenic. |
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| 12 | |
A stock of T4 phage is diluted by a factor of 10-7 and 0.1 ml of it is mixed with 0.1 ml of 108 E. coli/ml and 2.5 ml melted agar, and poured on the surface of an agar petri dish. The next day, 100 plaques are visible. What is the concentration (in plaque-forming units/ml) of T4 phages in the original T4 stock?
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| | A) | 107 pfu (plaque-forming units)/ml |
| | B) | 108 pfu/ml |
| | C) | 109 pfu/ml |
| | D) | 1010 pfu/ml |
| | E) | 1011 pfu/ml |
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| 13 | |
Shown below are the results of a series of coinfections using T4 rII- strains similar to those employed by Benzer in his deletion mapping experiment. Each strain contains a different deletion mutation. The ability to produce wild-type progeny phage is indicated by (+), (0) indicates no wild-type progeny.
| | A | B | C | D | E |
| | A | 0 | + | + | 0 | 0 | | B | + | 0 | + | 0 | + | | C | + | + | 0 | + | 0 | | D | 0 | 0 | + | 0 | + | | E | 0 | + | 0 | + | 0 |
Indicate the order that is most consistent with these data.
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| | A) | BEDCA |
| | B) | CEADB |
| | C) | ABCDE |
| | D) | CADBE |
| | E) | ACBDE |
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| 14 | |
Mutations that are in the same gene and do not complement each other are:
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| | A) | a complementation group |
| | B) | alleles |
| | C) | deletions |
| | D) | a and b |
| | E) | none of the above |
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| 15 | |
Assume four strains (A-D) of pure-breeding stippled lettuce have been isolated. Given the results of the following crosses:
A X C = stippled
A X B = wild type
A X D = wild type
B X C = wild type
B X D = stippled
C X D = wild type
What are the complementation groups for genes A-D?
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| | A) | A,B and D,C |
| | B) | A,C and B, D |
| | C) | A,D and C,B |
| | D) | A,B,C and D |
| | E) | A,C,D and B |
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| 16 | |
Assume 8 different strains of mouse have been isolated, each showing a recessive tail phenotype. Crosses are performed as follows; (+) indicates wild type, (0) indicates the behavioral trait.
| | A | B | C | D | E | F | G | H | | A | 0 | 0 | + | + | + | + | + | + | | B | | 0 | + | + | + | + | + | + | | C | | | 0 | + | 0 | + | 0 | + | | D | | | | 0 | + | + | + | + | | E | | | | | 0 | + | 0 | + | | F | | | | | | 0 | + | + | | G | | | | | | | 0 | + | | H | | | | | | | | 0 |
Based on these crosses, how many different genes are present?
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| | A) | 1 |
| | B) | 3 |
| | C) | 4 |
| | D) | 5 |
| | E) | 8 |
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| 17 | |
Assume 8 different strains of mouse have been isolated, each showing a recessive spinning behavior. Crosses are performed as follows; (+) indicates wild type, (0) indicates the behavioral trait.
| | A | B | C | D | E | F | G | H | | A | 0 | + | + | 0 | 0 | + | + | 0 | | B | | 0 | 0 | + | + | 0 | + | + | | C | | | 0 | + | + | 0 | + | + | | D | | | | 0 | 0 | + | + | 0 | | E | | | | | 0 | + | + | 0 | | F | | | | | | 0 | + | + | | G | | | | | | | 0 | + | | H | | | | | | | | 0 |
If you want to collect mutants for fine structure mapping, for which group (containing the gene listed) do you need more mutant strains?
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| | A) | A |
| | B) | F |
| | C) | H |
| | D) | B |
| | E) | G |
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| 18 | |
Consider the pathway for the synthesis of the amino acid arginine in Neurospora:
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| ARG-F
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| ARG-G
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| ARG-H
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| | ornithine
| →
| citrulline
| →
| succinate
| →
| arginine
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| e
| e
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Mutant strains of Neurospora are grown in minimal media with supplements as follows. Each mutant strain carries only a single mutation. Growth is shown by (+), no growth is shown by (0).
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Supplements
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mutant
strain
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nothing
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ornithine
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citrulline
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succinate
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arginine
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a
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0
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0
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0
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0
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+
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b
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0
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0
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0
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+
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+
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c
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0
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0
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+
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+
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+
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Indicate the correct strain / defective gene pairing.
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| | A) | strain a / ARG-G |
| | B) | strain a / ARG-F |
| | C) | strain b / ARG-G |
| | D) | strain c / ARG-H |
| | E) | strain c / ARG-G |
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| 19 | |
Assume that a series of compounds has been discovered in Neurospora. Compounds A-F appear to be members of an enzyme pathway. Several mutations have been identified and strains 1-5 each contains a single mutation. Shown below are 5 possible pathways. Choose the pathway that best fits the data presented. [growth in minimal media with supplements is shown by (+), no growth is shown by (0)]
| | media supplement |
| | strain | A | B | C | D | E | F |
| | 1 | 0 | 0 | + | + | + | 0 | | 2 | + | 0 | + | + | + | 0 | | 3 | 0 | 0 | 0 | + | + | 0 | | 4 | 0 | 0 | 0 | + | 0 | 0 | | 5 | + | 0 | + | + | + | + |
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| | A) | DECAFB |
| | B) | BFACED |
| | C) | BAFCED |
| | D) | DECFAB |
| | E) | CFBDEA |
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| 20 | |
What is the principal determinant of overall protein structure?
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| | A) | the carboxyl group. |
| | B) | the amino group |
| | C) | peptide bonds |
| | D) | amino acid sequence |
| | E) | none of the above |
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| 21 | |
An amino acid substitution in a protein can have:
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| | A) | a large effect on protein structure |
| | B) | a small effect on protein structure |
| | C) | little to no effect on protein structure |
| | D) | all of the above |
| | E) | none of the above |
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| 22 | |
An observable phenotype may arise from a change in:
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| | A) | the amino acid sequence |
| | B) | the control of protein expression |
| | C) | the amino acid sequence of an interacting subunit |
| | D) | all of the above |
| | E) | a and c |
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| 23 | |
A null allele can be dominant to the fully functional wild-type allele due to:
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| | A) | haploinsufficiency |
| | B) | codominance |
| | C) | incomplete dominance |
| | D) | neomorphism |
| | E) | not true, a null allele is always recessive to a fully functional wild-type allele |
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| 24 | |
Gene evolution is best illustrated by:
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| | A) | the rhodopsin gene family |
| | B) | inborn errors of metabolism |
| | C) | X-linked traits |
| | D) | sickle cell anemia |
| | E) | xeroderma pigmentosum |
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| 25 | |
Assume that for a given gene a mutation creates an allele that functions as a partially dominant negative as follows. The gene codes for a protein that forms a dimer within the cell. If one of the subunits has the mutant structure, the entire protein is 25% active. If both subunits are mutant, the enzyme is inactive. For a heterozygous individual, what percent of the normal activity is present in cells? |
| | A) | 12.5% |
| | B) | 25% |
| | C) | 37.5% |
| | D) | 50% |
| | E) | 75% |
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