Transcript Mutations

Mutation and Genetic
Change
Chapter 14.1
 Mutations= A change in the structure
or amount of genetic material of an
organism.
I. Causes of Mutations
 a. Accidental – caused during
cell division.
 b. Mutagens- caused by
environmental factors such as
radiation or chemicals.
II. Types of Mutations
a. Gene mutations- Changes within the
DNA sequence. (Smaller scale)
i. Point mutation- Change in one
single nucleotide (letter).
Original- THE CAT ATE RAT
Mutation- THE TAT ATE RAT
II Types of Mutations:
ii. Insertion- One or more nucleotides are
added into the sequence.
Original- THE CAT ATE RAT
Mutation- THE CAT AAT ERA T…
iii. Deletion- One or more nucleotides is
removed from the sequence.
Original- THE CAT ATE RAT
Mutation- T HC ATA TER AT…
II Types of Mutations
v. Missense mutation- A point mutation
that does throw off the amino acid
sequence.
vi. Frameshift mutation- A mutation
that shifts the entire sequence. All
insertions and deletions are considered
frameshifts.
vii. Nonsense mutation- When the
mutation accidentally causes the code
for a “stop” amino acid. This causes the
protein chain to be cut short.
II. Types of Mutations
II. Types of Mutations
b. Chromosomal
mutations- Mutation
in the number of or
parts of an entire
chromosome.
i. Deletion- When
part of a chromosome
or gene is removed.
Usually harmful.
II. Types of Mutations
ii. Duplication- When a
part of a
chromosome or
gene occurs twice
on the same
chromosome.
II. Types of Mutations
iii. Inversion- When
two genes on
the same
chromosome are
in reverse
order.
II. Types of Mutations
iv. TranslocationWhen a piece of
chromosome or a
gene ends up on a
completely
different
chromosome
II. Types of Mutations
v. NondisjunctionWhen the
chromosomes do
not “sort”
correctly during
meiosis. Usually
end up with an
extra
chromosome.
Mutations
c. Effects of Mutations
i.Heritability- Mutations are only able
to be inherited by offspring if they
affect an individual’s sex cells
(gametes).
ii. Cancer/tumors- Some mutations
cause somatic cells to lose control of
their cell division.
Mutations
iii. New alleles- New variations
of traits may occur (i.e. new
coat colors, new body shapes,
etc.).
iv. Genetic disorders- May
cause physical or mental
disabilities.
14.2 Regulating
Gene Expression
Gene regulation in
prokaryotes