Mutation - Lecture 2 Flashcards
What is a suppressor mutation?
a second site mutation that hides the effect of the first mutation
What is an intragenic suppressor mutation?
a supressor mutation that occurs in the same gene as the original mutation
What is an intergenic suppressor mutation?
a suppressor mutation that occurs in a different gene than the original mutation that generates a premature stop codon
What is the general range of mutation rates?
10^-4 to 10^-7
What are the types of spontaneous mutations that can occur?
DNA replication errors, DNA replication pausing, and endogenous chemical reactions
What mutations are considered DNA replication errors?
tautomeric shifts, base mispairing, and strand slippage
What is DNA replication pausing?
the generation of double-stranded breaks by ROS or topoisomerase
What are the types of endogenous chemical reactions?
Depurination, deamination, oxidation, and alkylation
What is depurination?
loss of a purine base from a nucleotide through hydrolysis of the glycosidic bond; can generate a transition or transversion mutation
What is deamination?
the spontaneous loss of NH2 group on DNA bases; causes transition mutations
What is oxidation mutation?
ROS damage DNA. to produce transversion mutations
What is alkylation mutation?
the addition of methyl groups to DNA bases to produce transition mutations
What are the types of chemical induced mutations?
Alkylating agents, hydroxyl amine, nitrous acid, base analogs, and acridines
What are alkylating agents?
chemical mutagens that react with bases to add methyl or ethyl groups
What effect does nitrous acid have on DNA?
its a deaminating agent
What effect does hydroxyl amine have on DNA?
it hydroxylates the amino group of cytosine causing the modified base to pair with adenine after replication, leads to a transition mutation
What effect do base analogs have on DNA?
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
What effect do acridine dyes have on DNA?
Intercalation of an acridine dye causes frameshift mutations during DNA replication
