Transcript Selective Breeding

Selective Breeding
Mrs. Wach
Selective Breeding
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This is the oldest type of genetic manipulation.
Breeding organisms for a desired characteristic.
Works very well in plants.
Also works with animals, but this can be more difficult.
Selective Breeding
• Mating animals to produce desired traits in offspring
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Racehorses
Dog breeds
Chickens
Variegated roses
Giant pumpkins
Seedless fruits
Inbreeding
• Inbreeding involves
crossing two closely
related individuals that
have similar desirable
characteristics.
• Inbreeding produces
organisms that are
genetically similar.
• When inbred organisms
are mated, the change of
their offspring inheriting
two recessive alleles
increase. This can lead to
genetic disorders.
Pure-Breed Animals
• Dogs, Cats, Horses,
etc.
• End up with many
problems- joint
issues, blindness, etc.
• “Mutts” are often
more healthy
Hybridization
• In hybridization, breeders
cross two genetically
different individuals.
(Remember, a hybrid
organism has two different
alleles for a trait.)
• The hybrid organism that
results is bred to have the
best traits from both
parents.
Horse + Donkey = Mule
Hybridization
• Liger is another example
Take this just a step further
• Scientists can hybridize
the genes by adding
DNA from one organism
to another organisms
egg (meta-cloning)
• Example: chickens that
are both meaty and
good egg layers
Cloning: Plants
• Cloning is used to produce
offspring with desired traits.
• A clone is an organism that
has exactly the same genes
as the parent.
• It is not hard to clone certain
plants, like African violets.
Just cut a stem from the
plant and put the stem in
soil. Water it, and soon a
new plant grows—being
genetically identical to the
parent plant.
Cloning: Ethics Issue
Dolly the Sheep (right)
5 July 1996 – 14 February 2003
• Dolly was the first mammal
to be cloned from an adult.
• The cell from the donor
was taken from a
mammary gland.
• Dolly had three mothers:
one provided the egg,
another the DNA and
another carried her to
term.
• Dolly lived for six years and
died from a common sheep
lung disease. Others in her
heard were infected.
(Normal life expectancy for
a sheep is 10-12 years.)
Genetic Engineering
Genetic engineering is the deliberate, controlled
manipulation of the genes in an organism with the intent of
making that organism better in some way.
Scientists use genetic
engineering techniques
to insert human genes
into the cells of cows.
The cows then produce
milk containing the
human blood-clotting
protein needed by
people with hemophilia.
Genetic Engineering in Bacteria
DIABETES: The DNA ring in a bacteria cell is spliced and the
human gene for insulin production is inserted into it. Now,
all future bacteria cells are capable of producing insulin.
Genetic Engineering in Plants
Genes have also been inserted into the cells of plants, such as tomatoes
and rice.
Some of the genes enable the plants to survive in cold temperatures or
in poor soil.
Other genetically engineered crops can resist insect pests or contain
more nutrients.
Genetic Engineering Gone Too Far?
• Genetic
engineering
is the
deliberate,
controlled
manipulation
of the genes
in an
organism
with the
intent of
making that
organism
better in
some way.
Gene Therapy
• Gene therapy is the genetic engineering that involves
inserting copies of a gene directly into a person’s cell to
treat genetic disorders in human.