Genetic Engineering
Chapter 13
Selective Breeding
• Choosing the BEST traits for breeding.
• Most domesticated animals are products
of SB.
• Also known as: Artificial Selection
• Techniques used in SB:
1. Hybridization
2. Inbreeding
HORSES
Hybridization
• Crossing dissimilar individuals to
bring together the best traits of both
organisms
• Produces hybrids
• * Hybrids can be different species crossed
together or different types within the same
species.
Golden Doodle and Puggle
Designer breeds or
mutts?
Can you think
of other fruit or
vegetable
hybrids?
Pluot
Broccoflower
Inbreeding
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Domesticated animals and plants are inbred to develop
“breeds” and “varieties.”
Researchers use inbred strains to assure genetic
similarities in their experiments.
Problems: it can increase the chance of unfavorable
traits showing up.
Golden retrievers - epilepsy
Dalmations - hereditary deafness
Increasing Variation
Breeders can increase variation in a
population by inducing mutations
Mutation = any change in DNA
Mutations can
happen
randomly, as in
this Scottish
fold cat. Cat
enthusiasts
bred these cats
from a single
cat with a
mutation for the
ears.
A new strain of Oil-eating
bacteria was produced.
Mutations can produce new kinds of plants
Ex: Plants can sustain multiple sets of
chromosomes - Polyploidy.
Manipulating DNA
• Making any changes in the DNA code is:
Genetic Engineering
How DNA is Manipulated:
• Extract DNA from cells
• Cut DNA into smaller pieces (Restriction
enzymes)
• Identify the sequence of bases in a DNA
molecule (Gel electrophoresis)
• Make unlimited copies of DNA strands(PCR)
• Combining different strands of DNA from
different organisms (recombinant DNA)
Transgenic Organisms
Definition: Organisms that contain
genes from another organism.
 Transgenic microorganisms – bacteria
that produce human insulin.
 Transgenic plants – major part of US
agriculture; weed resistance; insecticides
 Transgenic animals – growth hormones
in livestock, resistance to bacterial
infections, production of human proteins.
Transgenic animals
Gene causes these mice to glow
in the dark. Normally, the gene
is found in jellyfish.
Transgenic plants: GM crops!
Putting bacteria to work for us.
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Using recombinant DNA
The human Insulin gene
is inserted into the
bacterial DNA.
The bacteria now
produces human insulin
at a much faster pace
and cheaper than
animals can.
Cloning
clones – identical twins
 DNA must be identical to be a clone.
 Lifespan usually shortened.
 Health problems multiplied.
 Chance of survival before birth low.
 1997 Dolly the sheep cloned, 1st
mammal
 Natural
Figure 13-13 Cloning of the First Mammal
Section 13-4
A donor cell is taken from
a sheep’s udder.
Donor
Nucleus
These two cells are fused
using an electric shock.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
An egg cell is taken
from an adult
female sheep.
The fused cell
begins dividing
normally.
Embryo
Cloned Lamb
The embryo
develops normally
into a lamb—Dolly
Foster
Mother
The embryo is placed
in the uterus of a foster
mother.