Comprehension Questions

Section 18.1

Question 18.1

What is the difference between a transition and a transversion? Which type of base substitution is usually more common?

Question 18.2

Briefly describe expanding nucleotide repeats. How do they account for the phenomenon of anticipation?

Question 18.3

What is the difference between a missense mutation and a nonsense mutation? Between a silent mutation and a neutral mutation?

Question 18.4

Briefly describe two different ways in which intragenic suppressors can reverse the effects of mutations.

Section 18.2

Question 18.5

How do insertions and deletions arise?

Question 18.6

How do base analogs lead to mutations?

Question 18.7

How do alkylating agents, nitrous acid, and hydroxylamine produce mutations?

Section 18.3

Question 18.8

What is the purpose of the Ames test? How are his− bacteria used in this test?

Section 18.4

Question 18.9

What general characteristics are found in many transposable elements?

Question 18.10

How does a retrotransposon move?

Question 18.11

Draw the structure of a typical insertion sequence and identify its parts.

Question 18.12

Explain how Ac and Ds elements produce variegated corn kernels.

Question 18.13

What are some differences between class I and class II transposable elements?

Question 18.14

Why are transposable elements often called genomic parasites?

Section 18.5

Question 18.15

List at least three different types of DNA repair and briefly explain how each is carried out.

Question 18.16

What are two major mechanisms for the repair of double-strand breaks? How do they differ?

For more questions that test your comprehension of the key chapter concepts, go to for this chapter.