Download Genetic Engineering

Ch.12
Genetic Engineering
Genetic Engineering
• Genetic Engineering - It is now possible to
directly alter the genetic makeup of an
organism.
– Cutting DNA
– Changing DNA
– Removing and reinserting DNA
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Restriction Endonuclease
• Restriction Endonuclease – Recognizes and cuts
DNA at a particular sequence.
– EcoR1, BamI, HaeIII
Restriction Endonuclease
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Restriction Endonuclease
• Sticky Ends
– Unpaired DNA bases that result from a cut by a restriction
endonuclease.
– Can be attached to another molecule of DNA cut with the same
restriction endonuclease.
Sticky Ends
Restriction Endonuclease
Sticky Ends
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Restriction Endonuclease
Bacteria
• Bacteria
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Prokaryotes - lacks a nucleus
Simplest forms of life
Very small (nanometers)
Reproduce asexually
Most abundant and diverse
organism in the world.
– Some are helpful
• Photosynthetic bacteria, bacteria
in your large intestine, bacteria
on your skin, bacteria that
decompose dead organisms….
– Some are harmful
• Food poisoning, colds,
infections…
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Bacteria Structure
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No membrane bound organelles
Cell wall - maintains the cell’s shape
Capsule - helps the cell attach to surfaces.
Flagellum - some bacteria have one or more.
Pili - helps the cell stick to surfaces
DNA- one molecule of circular DNA
Bacteria Structure
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Plasmids – Small circular pieces of DNA found in
bacteria in addition to their chromosomes.
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Can be removed from bacteria and cut up using
restriction enzymes.
A DNA sequence can be inserted into a plasmid.
Plasmids can be easily reinserted back into bacteria.
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Bacteria Structure
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Plasmids carry genes for…
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resistance to antibiotics
resistance to heavy metals
sensitivity to mutagens
sensitivity or resistance to bacteriophages
production of restriction enzymes
production of amino acids
production of toxins
Cloning Genes By Using Bacteria
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Recombinant DNA – Combining DNA
from two different sources.
Transgenic organism - An organism
which contains foreign DNA
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Cloning Genes By Using Bacteria
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Transformation-inserting a plasmid which contains a
foreign gene into bacteria
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Remove a plasmid from a bacterium
Use a restriction endonuclease to remove a gene from an
organism - Create sticky ends!
Use the same restriction endonuclease to cut open the plasmidCreate sticky ends!
Insert the gene into the plasmid
Place the plasmid back into the bacterium
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Cloning Genes By Using Bacteria
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Reasons to do this
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Clone the gene - Many copies of the plasmid are made by
the bacteria as the bacteria reproduce
Express a protein such as insulin, human growth hormone,
interferon.
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Uses For Transgenic Organisms
• Transgenic Bacteria
– Researchers may need a particular protein in
large quantities for research.
– A pharmaceutical may wish to produce large
quantities of growth hormone or insulin.
– Bacteria which digests toxins and pollutants
such as oil and sewage.
Uses For Transgenic Organisms
• Transgenic Plants – Genes can be inserted
in to the plant DNA by a bacterium which
infects plants.
– Natural insecticides such as BT
– Plants which produce their own fertilizer
– Fruits and vegetables which don’t spoil as
quickly.
• Transgenic Animals – DNA is inserted
into the nucleus of a fertilized egg cell.
– Animals for research.
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Cloning an Entire Organism
• Clone – A newborn individual is a genetic
copy of the adult.
– Produce large numbers of organisms which
have favorable characteristics.
– Save an endangered species
• Remove the nucleus from an egg cell 
replace the nucleus with a nucleus from an
adult organism  Place the egg back into
the foster mother.
Cloning an Entire Organism
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Gel Electrophoresis
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Used to determine the size of DNA fragments
DNA samples are run through a porous gel called
agarose.
The DNA is pulled through the agarose by running
an electric current through the agarose gel.
DNA has a negative charge
DNA molecules migrate toward the anode which
has a positive charge
Large fragments of DNA move slowly through the
agarose while small DNA fragments move quickly.
A molecular weight marker is used to estimate the
size of the DNA fragments
Gel Electrophoresis
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Gel Electrophoresis
Gel Electrophoresis
• Uses for gel electrophoresis
– Identify similarities and differences among
different kinds of organisms.
– DNA fingerprinting.
– Separate DNA by size.
– Determine the sequence of an organism’s DNA
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Polymerase Chain Reaction (PCR)
• PCR = Polymerase chain reaction
• A lab technique which produces millions of
copies of DNA.
• Can be used for many applications
including
– DNA fingerprinting
– Diagnosis of diseases
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Gene Therapy
• Gene therapy - using
DNA in order to treat a
disease.
• A functional gene
replaces a mutated gene.
• Gene therapy treatments
are becoming more and
more successful as
research progresses.
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