Download Mutations

Mutations 12.4
Mutations
• On occasion, DNA polymerase makes a
mistake when replicating DNA.
• These mistakes cause a permanent change
in the DNA called a mutation.
• Most times mutations are harmless, but
sometimes they can be dangerous and
sometimes they can be beneficial.
Gene Mutations
• These mutations only affect a single gene
and few nucleotides within the genes.
• There are 2 types of gene mutations:
– Point mutations
– Frameshift mutations
Point Mutations
• Occur at a single point in the DNA sequence
• Often are harmless
• 1 Type
– Substitution
Substitution Gene Mutations
• This mutation occurs
when DNA polymerase
puts the wrong base pair.
For example instead of
putting a C, it puts a T.
• These mutations often are
harmless.
Frameshift Gene Mutations
• This mutation occurs
when either a base is
added (Insertion) or a
base is removed
(Deletion).
• For example, Insertion
occurs when an extra T
when it not needed
• These mutations almost
always change the protein
because the codons all
change after the mutation
Chromosomal Mutations
• Each chromosome contains several genes
on it.
• Chromosomal Mutations affect the entire
chromosome and could affect several genes.
Chromosomal mutation
Chromosomal Mutations
• Deletion can delete one
or multiple genes
• Duplication makes an
extra copy of a gene or
multiple genes
• Inversion changes the
order of the genes on a
chromosome
• Translocation switches
the genes between 2
chromosomes
Chromosomal Mutations
• Most chromosomal
mutations do not result in
loss of genetic material,
which makes them
generally harmless.
• Which chromosomal
mutation would be the
most harmful?
– Deletion