V. Mutations
A. What is a mutation?
1. A change in genetic material
a) Gene (point) mutation- a change in a
single gene
b) Chromosomal mutationa change in the number
or structure of the
chromosome
B. Gene (point) Mutations
1. To illustrate gene mutations, we’re going to use
this sentence as an example:
THEDOGBITTHECAT
THE DOG BIT THE CAT
B. continued
2. Point mutations: a change in one or a few
nucleotides on a DNA strand
3. 3 specific types we will discuss include:
a) silent mutation
b) substitution
c) Frameshift mutation (insertion & deletion)
4. Silent Mutations
a) Silent mutations: mutations that change the
DNA sequence, but don’t change the amino
acid sequence produced in protein synthesis.
– This has NO effect on an organism. Why?
THE DOG BIT THE CAT
THE DOG BIT THE KAT
5. Substitution Mutation
a) Substitution mutations do change the
sequence.
THE DOG BIT THE CAT
THE DOG BIT THE CAR
6. Frameshift Mutations
a) Two types of frameshift mutations:
– Insertions
– Deletions
b) Frameshift mutations cause MAJOR changes
to the amino acid sequence – since the
sequence is still read in groups of three.
6. Frameshift Mutations
we’re going to insert another “D”
THE DOG BIT THE CAT
THE DDO GBI TTH ECA
we’re going to delete this “D”
THE DOG BIT THE CAT
THE OGB ITT HEC AT_
C. Chromosomal Mutations
1. Deletions: occurs when a chromosome breaks and a
piece of a chromosome is lost.
Chromosomal Mutations
2. duplication– occurs when part of a chromosome
breaks off and is incorporated into another
chromosome.
Chromosomal Mutations
3. translocation – occurs when parts of two different
chromosomes swap positions.
Chromosomal Mutations
4. Inversions – occurs when part of a chromosome
breaks off, turns around, and reattaches in the
reverse order.
D. How to become
a mutant…
1. Can I become a
mutant?
a) Yes. Some mutations
are inherited but
others occur later in
life as a result of
mutagens.
b) Mutagens are things
that can cause a
change in DNA
sequences.
•
•
•
Radiation
Chemicals (think
teenage mutant ninja
turtles)
High temperatures