Lecture 31 Mutation Flashcards
Mutation
a heritable change in the genetic materialm
Mutant
a strain of any cell or virus carrying a change in nucleotide sequence
True or False: Mutations can be beneficial
True!
True or False: Most mutations are harmful
False! (most are netural)
Spontaneous mutations
occur without external intervention
What is the mutation rate per replicated gene?
10^-6 (several mutations can happen in a day)
Induced mutation
Mutations due to external forces
Point mutations
mutations that change only one base pair
What are point mutations caused by?
base pair substitution
What are the three types of base pair substitutions?
missense mutation, silent, nonsense mutation
Missense mutation
result in change in amino acid; possible phenotype change
Silent mutation
no change in amino acid sequence; no phenotype change
Nonsense mutation
introduces stop codon and produces truncated protein; effect on phenotype is very likely
Frameshift mutation
the insertion or deletion of one or more nucleotide pairs; changes codon reading frame and multiple amino acids; effect on phenotype is very likely
Mutagen
agent that causes mutations; can increase mutation rate
Classifications of mutagens
1) chemical mutagens (acridine dyes, nucleotide base analogs)
2) radiation (ionizing: xray/gamma rays & non-ionizing: UV)
True or False: bacteria have enzymes that can repair damage cause by mutagens
True!
Effect of acridine dyes
stretches DNA
Effect of nucleotide base analogs
substituted in; changes DNA base pairing
Effect of ionizing radiation
hydroxyl radicals
Effect of non-ionizing radiation
thymine diols
What does recombination create?
new combinations of genes even in the absence of mutation
How do mutations and recombination work together?
mutation and recombination fuel the evolutionary process; they provide genetic diversity
