Lecture 19: Gene Mutation
Before next lecture . . .
• Review this lecture (and background
material in Chapter 14) as needed
• Review Section 12.3 on chromosomal
mutation for next class
• Tutorial 5 has prep in advance . . .
What mechanism(s) explain his -
A mutation is a heritable change in
reversion to his in the Ames Test? double-stranded DNA sequence.
• common types of change in the DNA
i) Base substitutions
1 Spontaneous tautomeric shifts
change base pairing "rules"
Some mutagens are tautomerically Codon sequence corresponds to
unstable base "analogues" amino acid sequence
Thymine 5- Brciluracil
2 Silent mutations: changed codon Missense mutations: changed codon
specifies the same amino acid specifies changed amino acid
Mutated base pair from
in normal Mutated base pair from
Codon changed to another