1. DNA Mutations

3. Photo by: axway

6. Mutations Mutations are any change in the nucleotide sequence of DNA
Mutagens = physical or chemical agents that cause mutations

7. Mutations Two categories Produce changes in a single gene
Gene mutations
Produce changes to the whole chromosome
Chromosomal mutations

8. Gene mutations 3 types Involve changes in one or a few nucleotides
Known as point mutations
Generally occurs during replication
3 types
Substitutions
Insertions
deletions

9. Point mutations Substitution One base is changed to a different base
Usually doesn’t affect more than one amino acid
May not have an effect at all
EX: CCC to CCA (mRNA codon)
Both code for amino acid proline
CCC to ACC
Replace proline for the amino acid threonin

11. Insertions and deletions
One base is inserted or removed from the DNA sequence
Can be dramatic change
Codons are read 3 bases at a time, if a nucleotide is added or deleted the codon (3 base group) changes, it is shifted and all codons following change
Also known as frameshift mutation