Download mutation

DNA Mutations
What is a gene mutation?
 Often times, parts of DNA will have a
base (or more) missing, added, or
incorrect
Can be caused by: errors in replication,
transcription, cell division, or by
external agents (like radiation)
What is a gene mutation?
A mutation is any change in the Nucleic
Acid (DNA/RNA) sequence.
Any agent that can cause a mutation is a
mutagen.
Any mutagen that causes cancer is a
carcinogen
Any mutagen that causes birth defects is
a teratogen
Mutagens
Any agent that can cause a mutation
These are caused by factors in the
environment such as:
Radiation (x-rays, UV, nuclear)
Chemicals
Extremely high temperatures
Biological agents such as HPV
How common are mutations?
Mutations occurs at a frequency
of about 1 in every 1 billion base
pairs
Everybody has about 6 mutations
in each cell in their body!
The most common types of
mutations are:
Point Mutations
1. Substitution
2. Insertion w/ frameshift
3. Deletion w/ frameshift
Chromosomal Mutations
1.
2.
3.
4.
Deletion (a piece missing)
Duplication (a piece copied)
Inversion (a piece flipped)
Translocation (a piece moved to
another location)
DNA (Gene) Mutation
1. Substitution – a different base is
substituted for the original
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
What has happened in this mutation?
DNA (Gene) Mutation
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
*Adenine was accidentally
replaced with thymine
*What is this mutation called?
Substitution
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
What will happen to the amino acids?
Original DNA- ATC would code for : STOP
Mutated DNA of TTC would code for: Lysine
DNA (Gene) Mutation
2. Insertion with Frameshift - produce
extra copies of parts of a chromosome.
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
What has happened in this mutation?
DNA (Gene) Mutations
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
*Adenine was inserted, causing the
remaining DNA to shift to the right.
*What is this mutation called?
Insertion with Frameshift
Normal DNA: CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
What will happen to the amino acids?
DNA (Gene) Mutation
3. Deletion - loss of all or part of a
chromosome.
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
What has happened in this mutation?
DNA (Gene) Mutation
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
*Guanine was removed, causing the
remaining DNA to shift to the left
*What is this mutation called?
Deletion w/ Frameshift
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
What will happen to the amino acids?
What happens if
you accidently
skip an answer
on a scantron
sheet?
Substitution or Point Mutation
THE
THE
THE
THE
THE
THE
DOG BIT THE CAR
LOG BIT THE CAR
DOG BIT THE CAT
DOG HIT THE CAR
HOG BIT THE CAR
FOG BIT THE CAR
Insertion Mutation
THE DOG BIT THE CAR
THH EDO GBI TTH ECA R
Deletion Mutation
THE DOG BIT THE CAR
THE OGB ITT HEC AR
Gene mutations
4. Point mutations
Change one nucleotide or just a few nucleotides
in a gene
Examples: sickle cell anemia & cystic fibrosis
Cancer, color blindness
5. Frame-shift mutations
The reading pattern is displaced and “shifts” into
new positions
Examples: duchenne Muscular Dystrophy
Frame shift mutations
The cat and the rat ran far.
t
The ca and the rat ran far.
The caa ndt her atr anf ar.
Chromosomal mutations
6. Inversion = reverse the direction of parts
of a chromosome.
7. Translocation = occurs when part of one
chromosome breaks off and attaches to
another different chromosome.
Mutations: Changes in DNA
Advantages:
 New, stronger genes can
be passed on to offspring
Disadvantages:
 Abnormal, even lethal genes
can be passed on to offspring
Are they harmful?
b. Silent mutations – changes the nucleotide
sequence by has no effect on the synthesized
protein
c. Non-sense mutations – creates a protein
that is not usable. HARMFUL
Construct the Chart:
Cut out chromosomes to compete the chart
on Chromosomal Mutations
Chromosomal Mutations