Transcript Genetic Engineering

Genetic Engineering
• Genetic Engineering is the process of
making changes in the DNA code of living
organisms.
• Genetic Engineering and DNA
Technology can be used to
– Cure diseases
– Treat genetic disorders
– Improve food crops
– Produce vaccines and
other useful drugs
Genetic Engineering Includes
• Selective Breeding &
Crossbreeding
• Recombinant DNA
• Transgenic Organisms
• PCR
• DNA Fingerprinting
• Gel Electrophoresis
• Cloning
Selective Breeding
• Breed only those
plants or animals
with desirable traits
• People have been
using selective
breeding for
1000’s of years
with farm crops
and domesticated
animals.
Hybridization (Crossbreeding)
• Producing new organisms by the mating
individuals of different breeds, varieties, or
species
Male Donkey + Female Horse = Mule
Recombinant DNA
• rDNA has been artificially created
– DNA from two or more sources is recombined
into a single molecule
• To create rDNA, scientists use restriction
enzymes to cut DNA in precise locations
• Restriction enzymes
create “sticky ends” that
allow the DNA to bind to
another piece of DNA
with the same sticky ends
Recombinant Bacteria
1. Remove a Plasmid
– A plasmid is a small circular piece of DNA found in
bacteria
2. Cut the Bacterial DNA with restriction enzymes
3. Cut the desired gene from another organism’s
DNA with restriction enzymes
4. Combine the cut pieces of DNA together and
insert them into bacteria.
5. Reproduce the recombinant bacteria.
6. The foreign genes will be expressed in the
bacteria.
Recombinant Bacteria
Benefits of Recombinant
Bacteria
1. Bacteria can make human insulin or
human growth hormone.
1. Bacteria can be engineered to “eat” oil
spills.
Transgenic Organisms
• The genetic code is
universal, therefore it is
possible to make
organisms that are
transgenic
• Transgenic organisms
contain genes from other
species
• They are also called
GMO’s – Genetically
Modified Organisms
This tobacco plant glows in
the dark because scientists
gave it the gene that
causes fireflies to glow
Transgenic Plants
• Disease-resistant
and insect-resistant
crops
• Hardier fruit
• 70-75% of food in
supermarket is
genetically modified.
Transgenic Animals
• Mice – used to study human
immune system
• Chickens – more resistant to
infections
• Cows – increase milk supply
and leaner meat
• Goats, sheep and pigs –
produce human proteins in
their milk
Polymerase Chain Reaction
PCR
• PCR is a fast and inexpensive technique
used to amplify (copy) small amounts of DNA
1. Heat the DNA so it “unzips”.
2. Add the complementary nitrogenous bases.
3. Allow DNA to cool so the complementary
strands can “zip” together.
DNA Fingerprinting
• A technique used by scientists to
distinguish between individuals of the same
species using only samples of their DNA
• Unless they are identical twins, individual
organisms all have unique DNA.
• The chemical structure
of the DNA may be the
same (A, T, C & G), but
the order of the base
pairs is different
DNA Fingerprinting Process
• First, DNA must be obtained from blood, bodily
fluids, hair roots, skin, or elsewhere
• After the DNA is isolated, it is amplified using
PCR
• Then the DNA is treated with restriction
enzymes
– Cut the DNA at specific sequences
• This results in different sized fragments
• These fragments are separated, based on size,
using a process called Gel Electrophoresis
Gel Electrophoresis
• DNA fragments are
separated as they
migrate through an
agarose gel matrix
• This size-based
separation occurs
when an electric
current is applied
to the gel
Gel Electrophoresis
• DNA is a negatively charged molecule,
so it will move toward the positive end of
the chamber
• The smaller
fragments will move
faster and farther
than the larger
fragments
Gel Electrophoresis Steps
1. “Cut” DNA sample with restriction enzymes.
2. Run the DNA fragments through a gel.
3. Bands will form in the gel.
4. Everyone’s DNA bands are unique and can be
used to identify a person.
DNA Fingerprinting
• DNA fingerprinting can show which individuals
are the parents of specific children
– A child’s DNA fragments must be inherited from
his or her biological parents
DNA Fingerprinting
• DNA fingerprinting
can also be used to
help solve crimes
Cloning
• Cloning is the creation of an organism that
is an exact genetic copy of another
– Their DNA is identical
• Produced by asexual reproduction
– Mitosis
Cloning
• Dolly the sheep
was the first animal
to be successfully
cloned in 1997
• There were 277
failures before this
nuclear transfer
technique
succeeded