Chapter 15.1.3 (Exam 4) Mutations

Question 1

Do mutations outside of coding regions lead to phenotypic effects?

Answer 1

Mutations outside coding regions can have no effect or significant effects

Question 2

What are some regions that don’t code for protein?

Answer 2

Promoter mutations may alter the rate of transcription of the gene

Mutations at RNA splicing sites (consensus sequences) may lead to abnormal mRNA

Mutations in the introns may not have an effect

Question 3

What are chromosomal rearrangements?

Answer 3

DNA molecules can break and rejoin, grossly disrupting genetic sequences

Question 4

What are chromosomal rearrangements caused by?

Answer 4

Can be caused by damage to chromosomes by mutagens or by errors in chromosome replication

Question 5

What are the 4 chromosomal rearrangements?

Answer 5

Deletion

Duplication

Inversion

Reciprocal translocation

Question 6

What are spontaneous mutations? What is one example?

Answer 6

Spontaneous mutations occur with no outside influence, by several mechanisms

Example - Mistakes during replication

Question 7

What is induced mutation?

Answer 7

Induced mutation: agent from outside the cell (mutagen) causes a change in DNA

Question 8

What are some examples of mechanisms by which an induced mutation can occur?

Answer 8

Chemical mutagens can alter bases, e.g., nitrous acid can deaminate cytosine and convert it to uracil

Radiation can damage bases and unrecognizable by DNA polymerase

Question 9

What are 3 benefits of mutations?

Answer 9

They provide genetic diversity for natural selection

Mutations in somatic cells may benefit an organism immediately

Mutations in germ line cells may cause an advantageous change in the offspring’s phenotype