Chapter 15.1.1 (Exam 4) Mutations

Question 1

What is a mutation?

Answer 1

A change in the nucleotide sequence that can be passed on from one cell or organism to another

Question 2

What are two types of mutations based on where in the body they occur?

Answer 2

Somatic mutations - occur in non gamete body cells

Germ line mutations - occur in cells that give rise to gametes

Question 3

What are two types of mutations based on their effects on the phenotype?

Answer 3

Loss of function mutations

Gain of function mutations

Question 4

Describe loss of function mutations.

Answer 4

Gene is not expressed at all, or protein does not function

Nearly always recessive

Question 5

Describe gain of function mutations.

Answer 5

Produces a protein with altered function

Usually dominant

Common in cancer

Question 6

What is a conditional mutation?

Answer 6

Phenotype is altered only under certain (restrictive) conditions

E.g., a protein may be unstable at high temperatures

The mutation is not detectable under permissive conditions

Question 7

What is an example of a conditional mutation?

Answer 7

Point restriction phenotype in Siamese cats

Question 8

What are reversion mutations?

Answer 8

The gene is mutated a second time and results in one of two outcomes:

DNA reverts to the original sequence

DNA reverts to a different sequence that results in the non-mutant phenotype