1. Genetic Diversity: Natural
and Artificial Means
Honors Biology

2. Genetic Diversity
 The sorting and recombination of genes
in sexual reproduction results in a great
variety of gene combinations in the
offspring of any 2 parents.
 Do you look EXACTLY like your
brothers & sisters?

3. Genetic Diversity
 Genetically diverse populations are
more likely to survive changing
environments.
 Greater variation within the
species makes a population better
suited to adaptation to changes in
the environment.

4. Leopards and Genetic
Diversity
 Leopard populations
around the world are
in danger because of
inbreeding.
 There is very
little genetic
variation between
any 2 individuals.

5. Genetic Diversity
 This makes
them VERY
susceptible
to disease &
will likely
lead to their
extinction.

6. Genetics of Meiosis
 Recombination and mutation provide for
genetic diversity.
 Inserting, deleting, or substituting
DNA bases can alter genes.
 An altered gene in a sex cell may be
passed on to every cell that develops
from it, causing an altered phenotype.

7. Natural Recombination:
Crossing Over
 Occurs in A A a a
prophase of B B b b
meiosis I C C c c
D D
d
Generates
d

E E e e
diversity
F F f f
Creates chromosomes with new combinations of
alleles for genes A to F.

8. recombination
Letters denote A a a
A
genes B b b
Case denotes
B
C C c
c
alleles
D D
d d
E E e e
F F f f

9. recombination
A a A a
B b B b
END RESULT: Alleles C C c c
have crossed over to
produce new gene
combinations D D
d d
E E e e
F F f f

11. Trisomy 21
 Sometimes entire
chromosomes can
be added or
deleted, resulting
in a genetic
disorder such as
Trisomy 21 (Down
syndrome).

12. Genetic Diversity
 Chromosomal Errors
 NONDISJUNCTION: the failure
of chromosomes to separate
properly in meiosis. Gametes with
extra or too few chromosomes
result.
 Can cause diseases such as
Down’s Syndrome.

13. Other Chromosomal Mutations
 Chromosomal Errors
 POLYPLOIDY: organisms with
entire extra sets of chromosomes
 Results in the death of the fetus
in animals
 Often occurs in plants and causes
the fruits and flowers to be
larger. EX.: bananas, lilies

14. Karyotype
Boy or
Girl?

15. Genetic Diseases
Turner's Syndrome
 Turner’s syndrome is a genetic
disorder affecting only females, in
which the patient has one X
chromosome in some or all cells; or
has two X chromosomes but one is
damaged.

16. Genetic Diseases
Turner's syndrome
 Signs of Turner syndrome include:
 short stature,
delayed growth of the skeleton,
shortened fourth and fifth
fingers,
broad chest,
and sometimes heart
abnormalities.

17. Genetic Diseases
Turner's syndrome
 Women with
Turner
syndrome are
usually infertile
due to ovarian
failure.
 Diagnosis is by
blood test
(karyotype).

18. Turner’s Syndrome

19. Genetic Diseases
Huntington’s Disease
 Huntington’s disease (HD) is an
inherited disorder caused by the
degeneration of certain nerve cells in
the brain.
 The gene for Huntington’s disease is
codominant.
 HD causes bizarre involuntary
movements and loss of intellectual
abilities (dementia).

20. Genetic Diseases
Huntington’s Disease
 The condition begins most often in
mid-adulthood and progresses slowly
to death.

21. Huntington’s
Disease

22. Genetic Diseases
Tay-Sachs Disease
 A hereditary disease that affects
young children almost exclusively of
eastern European Jewish descent, in
which an enzyme deficiency leads to
the accumulation of fat in the brain
and nerve tissue.

23. Genetic Diseases
Tay-Sachs Disease
 Tay-Sachs results in:
 mental retardation,
 convulsions,
 blindness,
 and ultimately death.

24. Genetic Diseases
Tay-Sachs Disease

25. In the Laboratory: Changing DNA
 DNA technology is used to change life
every day!!!
 Gel Electrophoresis
 Transgenic organisms (Gene Splicing)

26. GEL ELECTROPHORESIS
 A lab procedure that sorts portions of
DNA by size
 Why? To determine gene length!!!
(Number of base pairs present in gene)

27. STEPS OF GEL
ELECTROPHORESIS
 DNA to be studied is cut into smaller
portions by an enzyme
 DNA is now in fragments.

28. 1. Fragments are placed in the (-) end of
a gel and an electrical current is sent
through the gel
FACT:
DNA is NEGATIVELY (-) charged. The
electrical current causes DNA to move
towards the (+) end of the gel, like a
magnet attracted to its opposite pole

30.  The electrical current separates DNA
fragments by size
 “Short” genes travel a long distance
across the gel
 “Long” genes travel a short distance
across the gel
THE SMALLER THE GENE, THE FURTHER
IT CAN TRAVEL ACROSS THE GEL!!!

31. As DNA moves across the gel, it
creates visible bands. . .

32. APPLICATIONS OF GEL
ELECTROPHORESIS
 DNA Fingerprinting: each individual’s
genes will create different bands when
put through electrophoresis
 Results can be used to:
 Determine a criminal’s innocence or guilt
 Determine the paternity of a child

34. TRANSGENIC ORGANISMS
 Created using GENE
SPLICING
 Definition: Any
organism that has
foreign DNA in its cells
 Why would someone
want to put foreign
DNA in an organism?

36. WHY???
 AGRICULTURAL IMPROVEMENT:
growth-hormone gene added to
organisms that don’t have it to increase
weight. Common practice in livestock.
 MARKETING: jelly fish gene. . .

38. CLONING
 Definition: Producing an organism
genetically identical to another
organism
 1997 – Sheep clone (Dolly) created by
extracting cells from a female sheep
 What does the future of cloning hold for
us???