Chapter 11: Mutation

Question 1

Which of the following
is true about mutations?

A) Mutations are random changes to DNA sequence
caused by replication errors, chemicals, or radiation
B) Mutations can affect a protein coding sequence or
how a gene is expressed
C) A mutation does not always change the phenotype
of the organism
D) All of the above are true

Answer 1

D) All of the above are true

Question 2

Mutations can be caused by:

Answer 2

• Spontaneous events
• Chemical mutagens
• Radiation

Question 3

Why are transition mutations
more common than transversions?

A) Transition mutations convert a nucleotide into
the nucleotide it pairs with
B) Transitions change a pyrimidine into a pyrimidine
or a purine into a purine
C) Transitions change a pyrimidine into a purine
D) All of the above
E) None of the above

Answer 3

B) Transitions change a pyrimidine into a pyrimidine
or a purine into a purine

Question 4

Which of the following is TRUE
with respect to mutations?

a) Transitions and transversions are equally likely
b) All substitutions are caused by chemical mutagens
c) All insertions, deletions, and rearrangements are
caused by spontaneous events
d) All of the above are true
e) None of the above are true

Answer 4

e) None of the above are true

Question 5

Which class of mutation results in a protein with the
same amino acid sequence as the wild-type
polypeptide?

a) Frameshift
b) Missense
c) Nonsense
d) Silent

Answer 5

d) Silent

Question 6

Which class of mutation is most likely to result in a
mutant phenotype?

a) Frameshift
b) Missense
c) Neutral
d) Silent

Answer 6

A) Frameshift

Question 7

Transcripts using the mutant “cryptic” splice site will:

a) have the same amino acid sequence as the wild-type protein.
b) have extra amino acids, but all other amino acids will be the
same as the wild-type protein.
c) have extra amino acids and different amino acids from the wild-
type protein.

Answer 7

c) have extra amino acids and different amino acids from the wild-
type protein.

Question 8

Which of the following is TRUE
with respect to random mutation?

a) An organism’s mutation rate depends entirely
on its environment.
b) Mutations that are beneficial for the organism
are more likely.
c) Mutations occur independent of their
phenotypic effect.

Answer 8

c) Mutations occur independent of their
phenotypic effect.

Question 9

Do Mutations Arise in Response to the Environment or Randomly?

Answer 9

Variations can exist prior to change in environment.

Question 10

Which of the following is TRUE about
Holliday Junctions and recombination?

A. Same sense resolution (2x EW or 2x
NS) causes gene conversion without
crossing over
B. Opposite sense resolution (1x EW and
1x NS) causes gene conversion without
crossing over
C. Same sense resolution (2x EW or 2x
NS) causes gene conversion and
crossing over
D. Opposite sense resolution (1x EW and
1x NS) causes crossing over without
gene conversion

Answer 10

A. Same sense resolution (2x EW or 2x
NS) causes gene conversion without
crossing over

Question 11

What is the role of p53?

Answer 11

Induces apoptosis in response to DNA damage.

Question 12

What is gene conversion?

Answer 12

Non-reciprocal transfer of genetic material during recombination.

Question 13

What is a tautomeric shift?

Answer 13

Spontaneous change in base structure causing mispairing.

Question 14

What is the effect of EMS?

Answer 14

Adds ethyl group to G → transition mutation.

Question 15

What does deamination lead to?

Answer 15

C/G → T/A transition.

Question 16

What does depurination lead to?

Answer 16

G/C → A/T transition.

Question 17

What is the main source of genetic variation?

Answer 17

Mutations.

Question 18

What is gene conversion?

Answer 18

Non-reciprocal transfer of genetic material during recombination.

Question 19

If you screen 1 million babies born to normal parents,
how many children do you expect to have aniridia?
A) 2.5
B) 5
C) 10
D) 20
E) 5 million

Answer 19

C) 10

Question 20

Are mutations directed by environment?

Answer 20

No, they occur randomly, independent of phenotypic effect.

Question 21

What experiment demonstrated random mutation?

Answer 21

Luria & Delbrück fluctuation test.

Question 22

What is an indel?

Answer 22

Insertion or deletion of nucleotides.