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Mutation Notes
Chapter 12-4
I. Mutations

A. Changes or mistakes in genetic
material (DNA)
 1. Some are good and some are
bad
 a) Good: make new traits
 b) Bad: change a protein
structure or gene
activity=disease
 B. Mutations can occur during Cell
Division (s-phase)
 1. Mistakes during DNA Replication
 C. Can happen in Body Cells or Sex Cells



1. Mutations can happen during Mitosis
(making of body cells)
2. The mutation only affects the person, not
the offspring
2. affects the function of the cell
 a)
Example: It causes the cell to not stop
reproducing (cancer)
 2.
Mutations can occur during
meiosis
 a) Meiosis is the making of
gametes (sperm or eggs)
b) These mutations affect the
offspring not the person
II. Types of Mutations
 A. Point Mutation: a change in a single
base pair in DNA.
 1.
May cause change in one single
amino acid or causes no change
at all.
2. Substitution: when a single
nucleotide is changed
 Ex:
 AUG AAG UUU GGC GCA UUG UAA




met
lys
phe
gly
ala
leu
stop
AUG AAG UUU _GC GCA UUG UAA
met
lys
phe
___
ala
leu
stop
 B. Frameshift Mutation: mutations
that cause a change in the entire
amino acid sequence following the
location of mutation.

1. Deletion: when a single nucleotide is
removed from DNA.
 Ex:
 AUG AAG UUU GGC GCA UUG UAA
 met
lys
phe
gly
ala
leu
stop
 AUG AAG UUG GCG CAU UGU AA
 met lys
___
___ ___ ___ ___

2. Insertion: when a single nucleotide is
inserted somewhere.

AUG AAG UUU GGC GCA UUG UAA
met lys phe gly ala leu stop



AUG AAG UUU GGC AGCA UUG UAA
met lys phe gly ___ ___ ___
 C. Chromosomal Mutations: Changes in
number or structure of chromosomes.
 1. Deletion or duplication of a piece of
chromosome.
a) depending on the information
disrupted or lost will determine the
effect of the mutation.


2. Inversion: a piece of the
chromosome will detach and reattach
in reverse order.
3. Translocation: a piece of a
chromosome will break off and
reattach to an entirely different
chromosome.
III. Causes of Mutations
 A. Mistakes during the cell cycle (DNA
Replication)
 B. Mistakes during Protein synthesis
(transcription or translation)
 C. Mutagens: any agent that causes a
mutation
 1. Ex: radiation, chemicals, high
temperatures, etc.