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Biol 3301: Genetics
Exam #3
Practice questions
1. (9) Match the word or phrase that best defines each statement:
h Mutation in which a purine is substituted by a pyrimidine a) Nonsense mutation
g Mutation caused by the addition of a base in a protein coding region b) Silent mutation
a A base change resulting in a stop codon c) Conditional mutation
e Type of mutation that causes mutant sectors to appear on a flower petal d) Auxotrophic
b A base change resulting in a codon specifying the same amino acid e) Somatic mutation
i Mutation in which a pyrimidine is substituted for a pyrimidine f) Lethal
c Mutation that causes a mutant phenotype only under restrictive conditions g) Frameshift
d A biochemical mutant that must be supplied with a certain nutrient for growth h) Transversion
f Mutation that causes death of the zygote i) Transition mutation
2. (3) What principle did the fluctuation test of Luria and Delbruck establish?
That mutations pre=exist within a population rather than being somehow induced by the
Selecting agent.
3. (3) What is the difference between mutation rate and mutation frequency?
Mutation rate is the number of mutations per unit of biological time (i.e. generation)
Mutation frequency is the number of mutations per unit of population.
4. (4) The rare enol form of thymine pairs with guanine. If a thymidine within the DNA helix shifts to the enol
form during replication, base pairing would change from a _____T-A______ base pair to a
______C-G_______ base pair.
5. (2) Tautomerization, depurination, deamination and oxidative damage are all sources of
___spontaneous____ mutations.
6. (2) In E. coli, a region flanked by two repeats of a sequence such as GTGGTGTAA is prone to
answer - a
a) Deletion b) Missense mutation c) Duplication d) Inversion e) Frameshift mutation
7. (2) The ionized form of 5-bromouracil will hydrogen bond to which base
answer - c
a) adenine b) cytosine c) guanine d) thymine e) uracil
