Download 12 Mutation Notes

Genetic
Mutations
Essential Question:
What are the causes and effects of mutations?
Mutation:
An unpredictable change in the genetic material
of an organism
Gene Mutation:
A change in the structure of a DNA molecule,
producing a different allele of a gene
(allele = version of a gene; ex: brown hair, black
hair)
Chromosome Mutation:
A change in the entire structure or number of
whole chromosomes
Which type of mutation has a larger
consequence? Explain why.
Causes of Mutations
Mutations occur randomly with no obvious cause.
Mutagens: Substances that increase the chances
of mutation occurring
Types of Mutations
1. Base Substitution – One nucleotide base
takes the place of another
• One amino acid is changed in the sequence
Effects of Base Substitutions
• Missense = if substitution changes amino
acid
• Nonsence = if substitution changes amino
acid into a “stop” codon
• Incorrect sequence of amino acids
What would happen if a base substitution
changed a codon from GGU to GGA?
Silent mutations – Mutation that has no
apparent effect on an organism OR does not
change the amino acid
What are the different possible affects
of base substitutions?
Types of Mutations (cont.)
2.
3.
Base Addition – (aka Insertions) One
or more extra nucleotide bases are added
to a sequence
Base Deletion – One or more
nucleotide bases are lost from the
sequence
**Both additions and deletions cause
Frame Shift Mutations
Types of Mutations
3.
Base Deletion – One or more
nucleotide bases are lost from the
sequence
Both additions and deletions cause
Frame Shift Mutations
(the codon “frame” shifts over one base and
the amino acid sequence changes for the rest
of the molecule)
• Incorrect sequence of amino acids
What could happen if one cell
developed a frame shift mutation
during replication today?
What would happen if
you were born with a
frame shift mutation in
one of your cells?