Download How can recombinant DNA be used?

Genetic Engineering
• Modifying an organism’s
genotype by introducing
genes from another
organism (often another
species)
This "autoluminograph" of a glowing
transgenic tobacco plant bearing the luciferase
gene of a firefly was first done in 1986
What’s Recombinant DNA?
Recombinant DNA – Refers to the
molecule formed by joining different
biological sources
Transgenic/Genetically Modified
Organism - An organism whose
genome has been modified by
introducing novel DNA
“Flavr Savr”
first sold in 1990s
How can recombinant DNA be used?
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Improved crops (drought & heat resistance)
Improved livestock
Animals with human genes for research
Prevention and cure of genetic diseases
Production of pharmaceuticals
Germ line and somatic gene therapy
Transgenic art (alba = part bunny, part jelly
fish)
Agricultural Uses: Plants & Animals
•Insecticide sweet corn- produces a poison which kills harmful insects
•Golden rice – vitamin A from gene in carrots adds nutrients to rice
•Frostban strawberries- protects strawberries from bacteria that cause
frost to form
•Pesticide resistant plants- pesticides will kills pests (weeds, insects, etc.)
but not plants
•Oncomous – mouse with a gene for cancer (for research)
•Pharming- inserting genes into livestock so they produce pharmaceutical
products (like insulin in milk)
•AquaAdvantage© Salmon – grow from egg to market size in half the time
MAKING RECOMBINANT DNA
MOLECULES:
1.
Cut large DNA molecules into smaller pieces with the use of
restriction enzymes
• These enzymes recognize specific DNA sequences that are 4-6
nucleotides in length.
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The enzyme is used by bacteria to destroy DNA of
invading viruses, but genetic engineers use the
enzyme to cut and paste DNA molecules from
different sources.
DNA TECHNOLOGY VOCAB
• SPLICING- cutting the DNA of a gene to add new base pairs
• VECTOR- transport vehicle which carries the desired gene into the host cell
• PLASMID- a small circular DNA molecule found in bacteria (separate from the
main bacterial chromosome)
• RESTRICTION ENZYME- a special DNA-cutting enzyme that is found in bacteria
• DNase- eukaryotic DNA-digesting enzymes
• DNA LIGASE- an enzyme that seals the gaps in the DNA
• DNA CLONING- making many copies of DNA (amplification) through the use of
a host bacterial cell
• RESTRICTION FRAGMENTS- Pieces of DNA of varying lengths
• GEL ELECTROPHORESIS- DNA fragments move through a porous gel in response
to an electric current (the smaller the fragment the faster it moves)
• DNA PROBE- a single-stranded DNA fragment that possesses a particular
sequence that is complementary to the fragment being sought. Sort of like a
guided missile.
Restriction Maps:
•A restriction map
is a description of
the restriction
cleavage sites
within a piece of
DNA
http://bio.classes.ucsc.edu/bio20L/info/animate/anim1/index.htm
2. Restriction enzymes generate a
“staggered cut” in the DNA
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This leaves short, single-stranded tails that
act as “sticky ends” that can bind with a
complementary single-stranded tail on
another DNA molecule.
•
since the restriction enzyme always
cuts a DNA molecule at the same
site in a sequence, it creates the
same sticky ends regardless of the
organism that donated the DNA.
3.
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Sticky ends from human
chromosomes readily
adhere to the
complementary singlestranded tails of the
bacterial plasmid that
has been cut with the
same enzyme.
When mixed together,
the complementary
sticky ends join the
isolated human gene
segment to the
plasmid.
4. DNA ligase acts as the tape to bond the DNA fragments together.
5. The Recombinant DNA is amplified by DNA
cloning.
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Place recombinant DNA molecule in a host bacterial cell to
replicate. Then recombinant DNA is purified and used in other
procedures.
6. If manufacturing the proteins, mammalian cells
(cultured in vitro) can also serve as hosts for
human genes.
SOME EXAMPLES
•insulin for diabetics
•factor VIII for males suffering from hemophilia A
•human growth hormone (GH)
•granulocyte-macrophage colony-stimulating factor (GM-CSF) for stimulating the
bone marrow after a bone marrow transplant
•angiostatin and endostatin for trials as anti-cancer drugs
•hepatitis B surface antigen (HBsAg) to vaccinate against the hepatitis B virus