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Chapter 15.1
Genetic Engineering
Selective Breeding
Biotechnology
• Biotechnology- manipulating the genetic
makeup of an organism
• Selective breeding
• Use of Mutations
Selective breeding
• Allowing only those organisms with desired traits
reproduce to form the next generation
• Hybridization – crossing dissimilar organisms to
bring out the best in both
– Offspring tend to be hardier than the parents
– Disease resistance with food-producing capacity
• Inbreeding – breeding organisms with similar
characteristics
– Dog breeds
– Increased likelihood that a genetic defect will result
because recessive alleles will likely come together
Hybridization – crossing two related species –
sometimes offspring are unable to reproduce
• Mule – male donkey
and female horse
• Henny – male horse
and female donkey
Cross Breeding – related species
Dog Breeds – an example of
inbreeding
Selective breeding can lead to
health problems in dogs
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Eye infections
Skin infections
Bone disorders
Inability to cool off
(large breeds)
• Inability to stay warm
(small breeds)
Variation
• Increase variation in a population by
introducing a mutation
– Bacterial mutations
• Exposing bacteria to a mutagenic agent in the
hopes that a useful mutant will result (ones that
might be able to clean up toxic waste)
– Polyploid Plants
• Plants with more than the diploid number of
chromosomes – larger and stronger plants
Chapter 15.2
Recombinant DNA
Changing DNA
• Recombinant DNA technology is the joining together
of DNA from 2 or more sources into one organism that
would not ordinarily have this DNA as part if its genome.
• This allows the genetic composition of the organism to
be changed – or “recombined”.
Recombinant DNA in Fish
• When the growth-hormone gene from a Chinook salmon,
the largest Pacific salmon species, and a "promoter"
gene from an Ocean Pout are added to the Atlantic
Salmon. The promoter gene keeps the fish's cells
making growth hormone around the clock.
• The result is an Atlantic salmon that reaches its mature
size in 16 – 18 months instead of the normal 30 – 36
months.
Comparison of Salmon Species
• Ocean Pout which gives the promoter gene:
• Chinook Salmon grows to about 125 pounds
• Atlantic Salmon grow to about 22 pounds.
Genetically Modified Salmon compared
to Non-genetically Modified Salmon
• Can you tell which is which?
Use of Bacteria in Recombinant
DNA Technology
• Bacteria contain small, circular portions of
DNA in addition to their chromosomes.
• These are called Plasmids.
• Plasmids are used in recombinant DNA
studies
Plasmid DNA Transformation
• Restriction enzymes cut DNA at specific
sequences producing “sticky ends” – when
both the target DNA and the plasmid are
cut with the same enzyme they will match
up
– In this way human DNA can be inserted into a
bacterial plasmid forming recombinant DNA
– The bacteria produce the protein coded for by the
human gene
– When bacteria divide, more of the human gene is
produced
How does “ligase” differ from
“restriction enzymes”?
Simulation
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Copying DNA
• 3 million restriction fragments would result if the
human DNA was cut with restriction enzymes
• Finding a single gene could be difficult
• Today genes can be located on computerized
databases
• Polymerase Chain Reaction (PCR) – a
technique used for copying a gene - allows for
an adequate amount of DNA to be available
when the original sample is too small to work
with
Transgenic Organisms
• Produced by inserting recombinant DNA into the
genome of a host organism
– Cloning – a single cell giving rise to an organism that
is genetically identical to the organism from which the
cell came
• Egg cell with nucleus removed
• Body cell fused into egg
• Fused egg and body cell begins to divide – becomes an
embryo
• Embryo inserted into uterus of a female
• Organism that is born is identical to the organism that gave
its body cell