Download Mutations Mutation: a random change in the sequence of

Mutations
Mutation: a random change in the sequence of nucleotides
in DNA
mutagen: a factor in the environment that causes a
mutation
examples:
radiation (nuclear, X-rays)
chemicals (tobacco)
UV rays (can cause skin cancer)
2 types of mutation:
1. chromosomal mutations: involve entire chromosome
2. gene mutations: involve individual genes
Chromosomal Mutations:
1. deletion: a piece of a chromosome breaks off and is lost
2. duplication: extra copy of part of a chromosome
 Usually, chromosomal mutations have huge effects. Most
deletions are lethal.
Gene Mutations:
1. frameshift mutation: nucleotides are lost or gained,
disrupting the codon sequence
Pat the bad cat. (delete 1 letter)
Ptt heb adc at  nonsense!
So if you’re reading codons and one base is lost, it can change
all the amino acids that are coded for after the deletion. It
could give an entirely different protein, or no protein at all.
2. Point Mutation: a change that occurs in only one
nucleotide
Ex. DNA has bases ATA mutation ATC
When the DNA is transcribed to mRNA, the mutation
can affect what amino acid is coded for.
DNA:
mRNA:
codes for:
ATA
UAU
tyrosine
mutation
ATC
UAG
STOP codon
1.
2.
3.
4.
Mutations: The Good, The Bad, and The Ugly
Sometimes mutations can have almost no effect on an
organism.
Sometimes mutations can kill an organism.
Sometimes mutations can be harmful to an organism but
not kill it.
Sometimes mutations can be helpful to an organism, giving
it a new gene that is an advantage.
examples:
 a mutation in a deer thaqt results in better
hearing
 a mutation in a rabbit that gives it thicker
fur in the winter
 a mutation in a squirrel that gives it bigger
mouth pouches to carry food
How is each one of these mutations helping the
organism to survive?