Transcript 12-4 Mutations - Lincoln Park High School

12-4 MUTATIONS
I. KINDS OF MUTATIONS
1. Mutation- change in
genetic material
that can result from
incorrect DNA
replication
2. Point Mutationsgene mutations that
result from changes
in one or a few
nucleotides
3. There are
three types
of point
mutations:
a) substitutions,
b) insertions,
c) deletions.
4. Substitutions usually affect only
one amino acid.
5. Frameshift Mutations- a type of
insertion or deletion
a)The addition or deletion of a
nucleotide causes a shift in the
grouping of codons
b)Can change every amino acid that
follows the point of the mutation
c) can change a protein so much that it
does not work normally
6. Insertion- an extra
base is inserted
into a base
sequence
7. Deletion-the loss
of a single base is
deleted and the
reading frame is
shifted
DISCUSS W/ PARTNER:
• Use the following DNA sequence
to show how it is changed by a
point mutation and a frameshift
mutation:
AAT
CGA
TCG
• Now write the mRNA sequence
and the protein sequence
produced by both of the
“mutated” DNA sequences
DISCUSS W/ PARTNER:
• Which type of mutation (point or
frameshift) is caused more
damage and why.
ANSWER:
• Frameshift causes more damage
because it changes all codons
after the point of the mutation.
The result is all of the amino acids
will be changed which can affect
the proper formation of a protein.
II. CHROMOSOMAL
MUTATIONS
1. Deletions-the loss of all or part of a chromosome
2. Duplications -produce extra copies of parts of a
chromosome
3. Inversions-reverse the direction of parts of
chromosomes.
4. Translocations - part of one chromosome breaks
off and attaches to another
III. SIGNIFICANCE OF
MUTATIONS
1. Many mutations have little or no
effect on gene expression
2. Some mutations are the cause of
genetic disorders
3. Good mutations may produce
proteins with new or altered activities
that can be useful
5. Polyploidy -the
condition in which
an organism has
extra sets of
chromosomes
Polyploidy in plants results in
plants that are larger & stronger
than diploid plants.