Download Mutations - Doral Academy Preparatory

DNA (Gene) Mutations
What is a gene mutation?
 Often times, parts of DNA will
have a base (or more) missing,
added, or incorrect
How common are
mutations?
Mutation occurs at a
frequency of about 1 in every
1 billion base pairs
Everybody has about 6
mutations in each cell in their
body!
If I have that many
mutations, why don’t I
look weird?
Mutations are not always seen.
Every part of your DNA doesn’t
make a protein or trait.
The most common types
of gene mutations are:
Substitution
Insertion
Deletion
DNA (Gene) Mutation
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TGC - TTC
What has happened to
the normal DNA?
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?
DNA (Gene) Mutation
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
What has happened to
the normal DNA?
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 (frameshift)
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TAG – CAT - C
What will happen to the
amino acids?
DNA (Gene) Mutation
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
What has happened to
the normal DNA?
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 (Frameshift)
Normal DNA:
CGA – TGC – ATC
Mutated DNA: CGA – TCA- TC
What will happen to the
amino acids?
Review
• What causes mutations?
Many mutations occur naturally (during DNA
replication)
Many mutations are caused by mutagens (UV
light, exposure to chemicals, radiation, etc.)
• What happens to a person who
has a mutation?
The mutation may be harmless (if it’s in junk DNA)
Some mutations can cause disorders
Review
• Which mutation would have the
least effect on an organism?
Substitution mutations have the least effect, because they
only affect ONE amino acid.
• When would a mutation have the
most effect on an organism?
Insertion and deletion mutations affect ALL proteins
after the mutation. Also, mutations in egg and
sperm can cause problems in offspring, whereas
mutations in body cells only causes problems for
that individual.
Review
• Do mutations get passed on to
offspring?
Only if the mutation ends up in the egg
or sperm. Mutations in body cells only
affect the individual- not his/her
children.
ReviewChromosomal Mutations
Any change in the DNA
sequence is known as a
mutation
Point mutations are
changes in a single base
pair in DNA
Frameshift mutations are
the insertion or deletion
of a single base causing
the sequence to shift one
way or the other
ReviewChromosomal Mutations
Great Websites
http://www.pbs.org/wgbh/aso/tryit/dna/i
ndex.html
http://www.dnaftb.org/dnaftb/22/animati
on/animation.html
http://www.biology.clc.uc.edu/courses/
bio104/dna.htm
http://www.johnkyrk.com/DNAanatomy.
html