Transcript 12.4 Mutations ppt

12.4 Mutations
Think About It!
Complete the 2 tables on the first page of your handout. Try
this without using your notes first and only refer to your
notes on transcription and translation if you are struggling.
From your tables and both translated sequences, what do
you think a mutation is?
What is a mutation? And what can
a mutation do?
 A mutation is a
permanent change in
the DNA sequence of
a gene.
 Mutations in a gene's
DNA sequence can
alter the amino acid
sequence of the
protein encoded by the
gene.
Mutation Types
Point mutations : single nucleotide base changes
in a gene's DNA sequence. This type of mutation
can change the gene's protein product in the
following ways:
3 Types of Point Mutations
1. Missense mutations
2. Nonsense mutations
3. Silent mutations
 Ex’s:
 Cystic Fibrosis
 Neurofibromatosis
 Sickle Cell Anemia
 Tay-Sachs
 Color Blindness
Missense Mutation
Result in a single amino acid change
within the protein.
Nonsense Mutation
-Create a premature “stop signal" (or
"stop" codon), causing the protein to
be shortened.
Silent Mutation
 Do not cause amino acid changes within the
protein.
Frameshift Mutations
 Change the grouping of
nucleotide bases into
codons.
 This results in a shift of
"reading frame" during
protein translation.
Insertion Mutation
Add a DNA Base
Deletion Mutation
Remove a DNA Base
But… mutations can also be beneficial
• Lactose Tolerance
• Antibiotic Resistance
• HIV Immunity
• Malarial Resistance from
Sickle Cell Anemia
Or they could be induced
• Mutagens
• Carcinogens
• Radiation
• UV light
• Environmental
• Heavy metals
• Chemical exposure
(VOC’s)
• Bacteria and Viruses
Skin Cancer
Skin cancer occurs when errors (mutations) form the
in the DNA of healthy skin cells. The mutations cause
the cells to grow out of control and form a mass of
cancer cells
The World Health Organization’s
International Agency for
Research on Cancer (IARC)
announced that it has moved UV
tanning beds to its highest
cancer risk category -"carcinogenic to humans."
The use of tanning beds
before age 30 is associated
with a 75% increase in
melanoma risk.
Lung Cancer
Smoking causes 87% of all lung cancer
cases. Smokers have approximately one
chance in 10 of developing lung cancer over
his/her lifetime.
Videos
Sickle Cell: http://www.dnalc.org/resources/3d/17-sickle-cell.html
Mutating virus: http://video.nationalgeographic.com/video/nationalgeographic-channel/shows/naked-science/ngc-deadly-mutation/
Radiation leading to mutations and cancer:
http://www.dnai.org/lesson/go/1738/1419
Addition and deletion mutations: http://highered.mcgrawhill.com/sites/0072556781/student_view0/chapter11/animation_quiz_4.html