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Genetic Diversity: Genetic Diversity: Natural and Artificial Natural and Artificial
MeansMeans
Honors BiologyHonors Biology
Genetic DiversityGenetic Diversity
The sorting and recombination of The sorting and recombination of
genes in sexual reproduction genes in sexual reproduction
results in a great variety of gene results in a great variety of gene
combinations in the offspring of combinations in the offspring of
any 2 parents.any 2 parents.
Do you look EXACTLY like your Do you look EXACTLY like your
brothers & sisters?brothers & sisters?
Genetic DiversityGenetic Diversity
Genetically diverse Genetically diverse
populations are populations are more likely to more likely to
survivesurvive changing changing
environments.environments. Greater variation within the Greater variation within the
species makes a population species makes a population
better suited to adaptationbetter suited to adaptation to to
changes in the environment.changes in the environment.
Leopards and Genetic Leopards and Genetic DiversityDiversity
Leopard Leopard
populations around populations around
the world are in the world are in
danger because of danger because of
inbreeding.inbreeding. There is very There is very
little genetic little genetic
variation variation
between any 2 between any 2
individuals.individuals.
Genetic DiversityGenetic Diversity
This makes This makes
them VERY them VERY
susceptible susceptible
to disease to disease
& will likely & will likely
lead to lead to
their their
extinction.extinction.
Genetics of MeiosisGenetics of Meiosis
Recombination and mutation Recombination and mutation
provide for genetic diversity.provide for genetic diversity.
Inserting, deleting, or substituting Inserting, deleting, or substituting
DNA bases can alter genes. DNA bases can alter genes.
An altered gene in a sex cell may An altered gene in a sex cell may
be passed on to every cell that be passed on to every cell that
develops from it, causing an develops from it, causing an
altered phenotype.altered phenotype.
Occurs in Occurs in prophase of prophase of meiosis Imeiosis I
Generates Generates diversitydiversity
Creates chromosomes with new combinations of alleles for genes A to F.
a
b
c
d
e
f
A
B
C
D
E
F
A
B
C
D
E
F
a
b
c
d
e
f
Natural Recombination: Natural Recombination: Crossing OverCrossing Over
Letters denote genes Case denotes alleles
A
B
C
D
E
F
a
b
c
d
e
f
c
d
e
f
A
B
a
b
C
D
E
F
recombinationrecombination
END RESULT: Alleles have crossed over to produce new gene combinations
A
B
C
D
E
F
a
b
c
d
e
f
c
d
e
f
A
B
a
b
C
D
E
F
recombinationrecombination
Trisomy 21Trisomy 21
Sometimes Sometimes
entire entire
chromosomes chromosomes
can be added or can be added or
deleted, deleted,
resulting in a resulting in a
genetic disorder genetic disorder
such as Trisomy such as Trisomy
21 (Down 21 (Down
syndrome).syndrome).
Genetic DiversityGenetic Diversity
Chromosomal ErrorsChromosomal Errors NONDISJUNCTION:NONDISJUNCTION: the failure the failure
of chromosomes to separate of chromosomes to separate
properly in meiosis. Gametes properly in meiosis. Gametes
with extra or too few with extra or too few
chromosomes result. chromosomes result. Can cause diseases such as Can cause diseases such as
Down’s Syndrome.Down’s Syndrome.
Other Chromosomal MutationsOther Chromosomal Mutations
Chromosomal ErrorsChromosomal Errors POLYPLOIDY:POLYPLOIDY: organisms with organisms with
entire extra sets of entire extra sets of
chromosomeschromosomes Results in the death of the Results in the death of the
fetus in animalsfetus in animals Often occurs in plants and Often occurs in plants and
causes the fruits and flowers to causes the fruits and flowers to
be larger. EX.: bananas, liliesbe larger. EX.: bananas, lilies
Karyotype
Boy or Girl?
Genetic DiseasesGenetic Diseases
Turner's SyndromeTurner's Syndrome
Turner’s syndrome is a genetic Turner’s syndrome is a genetic disorder affecting only females, in disorder affecting only females, in which the patient has one X which the patient has one X chromosome in some or all cells; chromosome in some or all cells; or has two X chromosomes but one or has two X chromosomes but one is damaged. is damaged.
Genetic DiseasesGenetic Diseases
Turner's syndromeTurner's syndromeSigns of Turner syndrome include:Signs of Turner syndrome include:
short stature, short stature, delayed growth of the delayed growth of the skeleton, skeleton,
shortened fourth and fifth shortened fourth and fifth fingers,fingers,
broad chest, broad chest, and sometimes heart and sometimes heart abnormalities. abnormalities.
Genetic DiseasesGenetic Diseases
Turner's Turner's syndromesyndrome
Women with Women with Turner Turner syndrome are syndrome are usually usually infertile due to infertile due to ovarian failure. ovarian failure.
Diagnosis is by Diagnosis is by blood test blood test (karyotype).(karyotype).
Turner’s Syndrome
Genetic DiseasesGenetic Diseases
Huntington’s DiseaseHuntington’s Disease
Huntington’s disease (HD) is an Huntington’s disease (HD) is an inherited disorder caused by the inherited disorder caused by the degeneration of certain nerve cells degeneration of certain nerve cells in the brain. in the brain.
The gene for Huntington’s disease The gene for Huntington’s disease is codominant.is codominant.
HD causes bizarre involuntary HD causes bizarre involuntary movements and loss of intellectual movements and loss of intellectual abilities (dementia). abilities (dementia).
Genetic DiseasesGenetic Diseases
Huntington’s DiseaseHuntington’s Disease
The condition begins most often in The condition begins most often in mid-adulthood and progresses mid-adulthood and progresses slowly to death. slowly to death.
Huntington’s Disease
Genetic DiseasesGenetic Diseases
Tay-Sachs DiseaseTay-Sachs Disease
A hereditary disease that affects A hereditary disease that affects young children almost exclusively young children almost exclusively of eastern European Jewish of eastern European Jewish descent, in which an enzyme descent, in which an enzyme deficiency leads to the deficiency leads to the accumulation of fat in the brain accumulation of fat in the brain and nerve tissue. and nerve tissue.
Genetic DiseasesGenetic Diseases
Tay-Sachs DiseaseTay-Sachs Disease
Tay-Sachs results in:Tay-Sachs results in:mental retardation, mental retardation, convulsions, convulsions, blindness, blindness, and ultimately death.and ultimately death.
Genetic DiseasesGenetic Diseases
Tay-Sachs DiseaseTay-Sachs Disease
In the Laboratory: Changing In the Laboratory: Changing DNADNA
DNA technology is used to change DNA technology is used to change life every day!!!life every day!!!
Gel ElectrophoresisGel ElectrophoresisTransgenic organisms (Gene Splicing)Transgenic organisms (Gene Splicing)
GEL ELECTROPHORESISGEL ELECTROPHORESIS
A lab procedure that A lab procedure that sortssorts portions of portions of DNA by DNA by sizesize
Why?Why? To determine To determine genegene lengthlength!!! !!! (Number of base pairs present in gene)(Number of base pairs present in gene)
STEPS OF GEL STEPS OF GEL ELECTROPHORESISELECTROPHORESIS
1.1. DNA to be studied is DNA to be studied is cutcut into into smaller portions by an enzymesmaller portions by an enzyme
2.2. DNA is now in DNA is now in fragmentsfragments..
2.2. Fragments are placed in the (-) end Fragments are placed in the (-) end of a gel and an electrical current is of a gel and an electrical current is sent through the gelsent through the gel
FACT:FACT:DNA is DNA is NEGATIVELYNEGATIVELY (-) charged. The (-) charged. The
electrical current causes DNA to electrical current causes DNA to move towards the (+) end of the gel, move towards the (+) end of the gel, like a magnet attracted to its like a magnet attracted to its opposite poleopposite pole
3.3. The The electricalelectrical currentcurrent separates separates DNA fragments by sizeDNA fragments by size
““Short” genes travel a Short” genes travel a longlong distancedistance across the gelacross the gel
““Long” genes travel a Long” genes travel a shortshort distancedistance across the gelacross the gel
THE SMALLER THE GENE, THE FURTHER IT THE SMALLER THE GENE, THE FURTHER IT CAN TRAVEL ACROSS THE GEL!!!CAN TRAVEL ACROSS THE GEL!!!
As DNA moves across the gel, it creates visible bands. . .
APPLICATIONS OF GEL APPLICATIONS OF GEL ELECTROPHORESISELECTROPHORESIS
DNADNA FingerprintingFingerprinting: each individual’s : each individual’s genes will create different genes will create different bandsbands when put through electrophoresiswhen put through electrophoresis
Results can be used to:Results can be used to:Determine a criminal’s Determine a criminal’s innocenceinnocence or or guiltguiltDetermine the Determine the paternitypaternity of a child of a child
TRANSGENIC TRANSGENIC ORGANISMSORGANISMS
Created using GENE Created using GENE SPLICING SPLICING
Definition: Definition: Any Any organism that has organism that has foreign DNA in its cellsforeign DNA in its cells
Why would someone Why would someone want to put foreign want to put foreign DNA in an organism?DNA in an organism?
WHY???WHY???
AGRICULTURAL IMPROVEMENT:AGRICULTURAL IMPROVEMENT: growth-hormonegrowth-hormone gene added to gene added to organisms that don’t have it to organisms that don’t have it to increase increase weightweight. Common practice . Common practice in livestock.in livestock.
MARKETINGMARKETING: jelly fish gene. . .: jelly fish gene. . .
CLONINGCLONING
Definition: Definition: Producing an organism Producing an organism genetically identical to another genetically identical to another organismorganism
1997 – Sheep clone (Dolly) created by 1997 – Sheep clone (Dolly) created by extracting cells from a female sheepextracting cells from a female sheep
What does the future of cloning hold for What does the future of cloning hold for us???us???