or How a perfectly good system can go wrong go wrong go wrong There are 2 types of mutations 1Chromosomal rearrangements There are too many or too few chromosomes nondisjunction and polyploidy ID: 426651
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Slide1
MutationsorHow a perfectly good system can go wrong go wrong go wrongSlide2
There are 2 types of mutations
1)Chromosomal rearrangements. There are too many or too few chromosomes. (nondisjunction and polyploidy)
Part of the chromosome is flipped on the same chromosome, or taken away or rearranged on a different chromosome (Inversion, deletion, translocation)
2)Gene Mutations. (occur on the DNA)
__One of the base pairs is
substituted with another
(point mutation)
__ A new base pair is Added (frame shift insertion)
__ One of the base pairs is deleted (frame shift deletion)
Slide3
MutationsMutations are the original source of all variations.
Each mutation changes the allele frequency of a gene in a population.WE
are all born with at least 3 mutations.Mutations in somatic cells are passed on to daughter cells in that organism . (E.g. 1 skin cell to another.)
Mutations in sex cells are passed on to the gametes
then zygotes. In other words all offspring.
(
That’s why the dentist puts a lead apron on your lap when you have an X-Ray.)Slide4
Plants VS AnimalsPlants can breed both sexually and asexually
Any mutation can be passed on to offspring.
Animals mostly reproduce sexuallyIn animals mutations can only be passed on to children if they happen in your gametes.If the mutation is large the zygote dies.
If it is a small mutation the zygote survives.Slide5
Are mutations bad?Why do they persist in populations?
Whether or not a mutation is harmful or beneficial can depend on the environment.
Sickle-Cell anemia is very prevalent in equatorialAfrica. So is Malaria. Both kill.
Let N= normal RBC Let n= sickled RBC
NN
Nn
nn
Is protected from SCA Is protected form Is killed by SCA
Is killed by Malaria both Is protected from MalariaSlide6
Some mutations occur spontaneously
Dwarfism: Half of all dwarfism genes are newly mutated.Hemophilia: A sex linked trait. Your blood does not clot. So you can easily bleed to death from a bump.
This gene is detrimental to health. Why doesn`t it just die out?Mutations just keep happening.
3 out of every 100,000 gametesSlide7
Nondisjunctionin one pair of chromosomes
Sometime in meiosis 1 one set of chromosomes will stick together and one egg will get egg will get 2 and the other will get none.
If this egg is fertilized the egg will either have 3 chromosomes (trisomy)Or 1 chromosome (
monosomy
)Slide8
Down`s syndromeTrisomy 21Slide9
Polyploidyoccurs in all chromosomes
Normally we have 2 sets of each chromosome. This is called diploid. If meiosis stops half way through you can get a diploid gamete.
diploid gamete.
+
+
=
=Slide10
When Polyploidy occurs in Plants it makes a stronger healthier, more rigorous plant.Most of the fruit, and grains you eat are polyploidy. The strawberries we pulled DNA from were
octoploidy, 8 sets of chromosomes.
When polyploidy occurs in animals it is almost always lethalSlide11
Gene MutationsPoint mutation is a substitution of 1 base for another.
Triplicate code
Amino Acid
A
U
G
Methionine
G
C
C
Alanine
U
U
A
Leucine
C
A
G
Glutamine
U
G
A
Stop
Triplicate code
Amino acid
A
U
G
Methionine
G
C
GAlanine
UUG
LeucineCC
AGlutamine
UAAStop
IF it mutation is in the
third base of the triplicate code,It doesn`t make much difference.
You can spell the amino acid many ways.Slide12
If you change the 2nd
letter in the triplicate code sometimes it makes a difference and sometimes not.
Triplicate code
Amino Acid
A
U
G
Methionine
G
C
C
Alanine
U
U
A
Leucine
C
A
G
Glutamine
U
G
A
Stop
Triplicate code
Amino Acid
A
U
G
Methionine
G
ACAspartic Acid
UCA
SerineC
AGGlutamine
UAA
StopSlide13
If you change the first letter of the triplicate code there are always major effects.
Triplicate code
Amino Acid
A
U
G
Methionine
G
C
C
Alanine
U
U
A
Leucine
C
A
G
Glutamine
U
G
A
Stop
Triplicate code
Amino Acid
A
U
G
Methionine
C
C
CProline
GU
AValine
GAG
GlutamineU
GAStopSlide14
Frame shift mutationsThese are very detrimental and the organism rarely survives.
Deletions
Jan can see her new hat
Let`s delete the n.
Everything else must move over.
Jan
cas
eeh
ern
ewh
at_
the entire gene is changed and makes no sense.
Insertions
Jan can
n
see her new hat
let`s insert another n and see what happens?
Jan can
nse
ehe
rne wha t_ _ still no good major change