Mutation - Lecture 2

Question 1

What is a suppressor mutation?

Answer 1

a second site mutation that hides the effect of the first mutation

Question 2

What is an intragenic suppressor mutation?

Answer 2

a supressor mutation that occurs in the same gene as the original mutation

Question 3

What is an intergenic suppressor mutation?

Answer 3

a suppressor mutation that occurs in a different gene than the original mutation that generates a premature stop codon

Question 4

What is the general range of mutation rates?

Answer 4

10^-4 to 10^-7

Question 5

What are the types of spontaneous mutations that can occur?

Answer 5

DNA replication errors, DNA replication pausing, and endogenous chemical reactions

Question 6

What mutations are considered DNA replication errors?

Answer 6

tautomeric shifts, base mispairing, and strand slippage

Question 7

What is DNA replication pausing?

Answer 7

the generation of double-stranded breaks by ROS or topoisomerase

Question 8

What are the types of endogenous chemical reactions?

Answer 8

Depurination, deamination, oxidation, and alkylation

Question 9

What is depurination?

Answer 9

loss of a purine base from a nucleotide through hydrolysis of the glycosidic bond; can generate a transition or transversion mutation

Question 10

What is deamination?

Answer 10

the spontaneous loss of NH2 group on DNA bases; causes transition mutations

Question 11

What is oxidation mutation?

Answer 11

ROS damage DNA. to produce transversion mutations

Question 12

What is alkylation mutation?

Answer 12

the addition of methyl groups to DNA bases to produce transition mutations

Question 13

What are the types of chemical induced mutations?

Answer 13

Alkylating agents, hydroxyl amine, nitrous acid, base analogs, and acridines

Question 14

What are alkylating agents?

Answer 14

chemical mutagens that react with bases to add methyl or ethyl groups

Question 15

What effect does nitrous acid have on DNA?

Answer 15

its a deaminating agent

Question 16

What effect does hydroxyl amine have on DNA?

Answer 16

it hydroxylates the amino group of cytosine causing the modified base to pair with adenine after replication, leads to a transition mutation

Question 17

What effect do base analogs have on DNA?

Answer 17

5-bromouracil (resembles T) and 2-aminopurine (resembles A or G)
Incorporated into DNA during replication and cause transition mutations
Keto 5-BU will pair with adenine but enol 5-BU will pair with guanine

Question 18

What effect do acridine dyes have on DNA?

Answer 18

Intercalation of an acridine dye causes frameshift mutations during DNA replication