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Content-Location: file:///C:/C9764A33/Mutations_files/master03.xml
Content-Transfer-Encoding: quoted-printable
Content-Type: text/xml; charset="utf-8"
![](3D"slide0001_background.jpg")
Big Trouble in Small =
Packages
MUTATIONS=
![](3D"slide0002_image003.jpg")
What
is a “mutation”?
•A
permanent change in the genetic code.
![](3D"slide0002_image005.jpg")
A “grey
factor” mutant
![](3D"slide0002_image006.gif")
A “comic
factor” mutant
Causing Mutations
Come from two places:
•
Mutagens: thing=
s that
cause changes in DNA
UV radiation
Other nuclear=
radiation
Other compounds
1. =
You
inherit them (thanks mom and dad)
OR
![](3D"slide0016_image007.gif")
![](3D"slide0016_image008.gif")
![](3D"slide0016_image009.gif")
![](3D"slide0016_image010.gif")
Gene
Mutations
•Involve base-pair changes
within a single gene
“What’s a gene again?”
![](3D"slide0003_image011.gif")
A segment of DNA that codes fo=
r a
polypeptide/protein
![](3D"slide0003_image012.jpg")
Substitutions
•These mutations involve replacing one
base with another.
•Only affect a single codon and, thus,=
a single
amino acid change…maybe.
=
Thesudwashotbuttheoldmandidnotgethishat.
=
Thesunwashotbuttheoldmandidnotgethishat.
=
The
sun was hot but the old man did not get his hat.
=
The
sud =
was hot but the old man did not get his hat.
Let’s make it easier to s=
ee
the message
Codons: Three-letter words
Here’s a substitution.
Do you still understand some of=
the
sentence?
Let’s make it easier to s=
ee
the message again.
Not sooooo bad. How ‘bout with real bases?<=
/div>
=
Since
The DNA code is a sequence of three-base codons, we =
can think of a gene as a sentence made up of
three-letter words
![](3D"slide0017_image013.gif")
C
G
C
C
G
C
G
C
G
A
T
A
U
A
T
G
C
G
G
C
G
U
A
T
A
T
A
A
T
A
U
A
T
A
T
A
A.A
RNA
compliment
Original
Silent Mutations
•If the change in sequence doesn’=
;t
alter the shape of the protein.
•Some changes in bases occur in region=
s of
“junk DNA” that don’t code for anything,<=
/span>
“Frameshift”
mutations
Adding or deleting a base.
•
Affect all=
following codons.
•
Often have profound effects on the organism.
<=
/span>
•
Lethal Mutations: Changes that are so damaging the organism cannot survive.
=
Thesunwahotbuttheoldmandidnotgethishat.
=
Thesunwashotbuttheoldmandidnotgethishat.
=
The
sun =
wah otb utt heo ldm and idn otg eth ish at.
Let’s really mess with the
message
Codons: Three-letter words continued
Here’s a deletion.
Now let’s look at the mes=
sage
as three letter words.
If that makes sense to you, I
cannot help you.
![](3D"slide0010_image014.gif")
C
G
C
C
G
C
G
C
G
A
T
A
U
A
T
G
C
G
G
C
G
U
A
T
A
T
A
A
T
A
U
A
T
A
T
A
A.A
RNA
compliment
Original
![](3D"slide0011_image016.jpg")
•Changes
that involve whole chromosomes
= (or at least parts of ‘em)
= (or at least parts of ‘em)
Chromosomal Mutations
![](3D"slide0012_image018.jpg")
Chromosomal Mutations
NON-DISJUNCTION=
![](3D"slide0012_image019.gif")
Resulting gametes and the zygotes they may form will have the wrong number of chromosomes.
During me=
iosis
(gamete formation) homologous pairs of chromosomes fai=
l to
separate.