Download Genetic Engineering and Recombinant DNA Technology

Genetic Engineering and Recombinant
DNA Technology
• Diversity of life is based on the differences
in genes (DNA)
• 1 gene = 1 protein = 1 function?
• If we change the DNA (genes), then it
would be possible to change the function
of the cell, and ultimately the organism
Genetic Engineering and Recombinant
DNA Technology
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Recombinant DNA-isolating and
combining DNA of one organism with
the DNA of a different organism
Human Insulin gene  bacteria
Genetic Engineering-modifying
gene(s) to benefit or cure an
organism
Agriculture crops, animals
Gene therapy: when cloned genes
are used to modify humans, to
control genetic diseases  sickle cell,
hypercholesterolemia
Ice cream anyone?
GloFish
Cloning Genes
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Cloning-production of
genetically identical DNA
To clone a gene, must
combine human DNA with
another organism’s DNA
 recombinant DNA
Put gene into a plasmid
 extra bacterial
chromosome that can
accept foreign DNA
Molecular Tools Used For Recombinant
DNA
• How to combine the DNA from 2 different
organisms?
• DNA must be cut and put back together
• What kind of molecule could cut DNA and put
it back together again?
Molecular Tools Used For Recombinant DNA:
Restriction Enzymes
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Bacterial enzymes that cut DNA
at specific DNA sequences
Leaves single stranded tails at
the end of the DNA fragments
 ”sticky ends”
DNA fragments cut by same
enzyme will come together and
form a 2x strand DNA fragment;
sticky ends are complementary
DNA ligase closes the “nicks” in
the DNA
Molecular Tools Used For Recombinant DNA:
Polymerase Chain Reaction (PCR)
• Multiple copying of a specific DNA sequence
Requires:
• primers
• Heat insensitive DNA polymerase from Thermus aquaticus (Taq)
• Used when only have small amounts of DNA and need to do many
different tests; genetic identification
Cycle 30 =
5.37 x 108
Genetic Fingerprinting
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Every person has specific DNA
sequences that are unique; like
fingerprints
During a criminal investigation,
those are the sequences that
are studied using restriction
enzymes, PCR and gel
electrophoresis
Gel electrophoresis-isolation of
DNA using electrical currents
and a gel matrix made of sugars
Genetic Fingerprinting: Gel
Electrophoresis
DNA has (-) charge, it will run towards the bottom of gel that
has (+) charge
Fragments separate based on size. Match fragment pattern
with DNA found at scene.
Take DNA found at crime scene
Restriction enzymes, STRs, PCR
Gel electrophoresis
Compare DNA fragmentsname suspect
DNA Sequencing
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Allows for the actual nucleotide sequence to be known
Automated, done by machines
Used to “solve” all the genes in humans Human Genome Project
Is there an advantage to knowing the entire gene sequence of an organism?
Functional genomics and comparative genomics
Applications of
Genetic Engineering
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In agriculture:
Strawberries that resist frost
rice with beta carotene
tomatoes that last longer
pest resistant corn (95% modified)
Larger animals more meat, milk
In environment:
Bacteria that clean up oil/toxic spills
In medicine:
Insulin, growth hormone, interferon,
taxol, relaxin, erythropoietin
Genetic Engineering
Problems:
• Is it safe for human consumption? Allergies?
• If organisms get out into natural setting,
impact environmental balance?
• Bigger animalsmore waste, competition
• Hybrids: herbicide resistance gene in corn
passed to a weed
The “Enviropig” has been genetically modified
in such a manner that its urine and feces
contain almost 65 percent less phosphorus
than usual.
Gene Therapy
 Introducing the normal gene into humans
with disease
 We can make the genes through rDNA,
but how do we get them inside to every
cell?
 Ex vivo gene therapy uses modified
viruses to get the new gene inside cells 
SCID, familial hypercholesterolemia
 In vivo gene therapy uses direct injection
or inhalation of normal/healthy gene to
defective cells/organs
 How do we prevent an immune reaction?