Disorders and dna technology

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?


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.


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).


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.


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.


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


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).


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


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.



Tay-Sachs results in:Tay-Sachs results in:mental retardation, mental retardation, convulsions, convulsions, blindness, blindness, and ultimately death.and ultimately death.



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???

Technology

Disorders and dna technology