Download DNA Technology

Biotechnology
Use of Natural Biological
Systems to Produce a Product
or Provide a Desired Process
Recombinant DNA Technology
• A set of techniques used to
produce large quantities of a gene
and its product
• Recombinant DNA = DNA
produced by joining segments of
DNA from different sources
• eg. To produce human insulin,
scientists have combined bacterial
DNA + human DNA
Tools for Producing
Recombinant DNA
Restriction enzymes: enzymes that
cleave the DNA double helix at
specific nucleotide sequences
Use of the Restriction Enzyme
Bam H1
5’— G G A T C C — 3’
3’— C C T A G G — 5’
Results in
sticky end
5’— G
3’— C C T A G
sticky end
G A T C C — 3’
G — 5’
Tools for Producing
Recombinant DNA
Vector: carrier of DNA; can be virus or plasmid
Plasmid: extrachromosomal, independently
replicating, small circular DNA molecule
Producing Recombinant DNA
Mix together
Add DNA Ligase
restriction
enzyme
Treat source
DNA with
restriction
enzyme
Treat plasmid
DNA with
same enzyme
Many recombinant DNA
molecules are produced,
each with a different
piece of source DNA
restriction
enzyme
Transform
bacterial cells
Each bacterial cell
carries a different
recombinant plasmid
Tools for Producing
Recombinant DNA
Probe: sequence of DNA that is
complementary to the gene of interest;
Used to locate a copy of the gene by
hybridization
AGCTTAGCGAT
TCGAATCGCTA
Denature DNA by heating
Add Probe
Probe Binds to gene
AGCTTAGCGAT
AATCGC
TCGAATCGCTA
Using the Probe to Find
the Gene of Interest
Biotechnological Methods: PCR
http://www.dnalc.org/resources/animations/pcr.html
PCR = Polymerase Chain Reaction
 Amplifies a specific region in the DNA
 Used for identification, especially
if the amount of DNA is small
 Uses repeated cycles of heating to
denature DNA and cooling to synthesize
new DNA
Involves the use of
---Taq polymerase (a DNA polymerase
that withstands heat)
---primers to begin synthesis
DNA Fingerprinting with PCR
DNA Fingerprinting for Paternity Testing
DNA Fingerprinting in Forensics
1 2 3
Suspects
CS
RC
IE
MN
EE
4 5 67
Suspects
Biotechnological Methods
DNA Sequencing: Determining the Order of Nucleotides
DNA sequence for gene
from cress plant
Arrows show differences
in DNA sequences related
to inherited breast cancer
Human Genome Project
• An effort to determine the sequences of
all human genes
– Genomics: study of DNA sequences
– Proteomics: study of proteins produced in
a specific organism or cell type
– Bioinformatics: using computer databases
to store and analyze sequence information
Applications of Biotechnology
Transgenic Bacteria
Transgenic: organism that contains a
gene from another species in all of its
cells
Transgenic bacteria that produce
Human Insulin
Human growth factor
tissue plasminogen activator (t-PA)
hepatitis B vaccine
Applications of Biotechnology
Transgenic Plants
Bt Corn: Produces
its own Pesticide
Roundup Ready Soybeans
are resistant to herbicide
“Golden” rice with
beta-carotene and
extra iron
Applications of Biotechnology
Transgenic Animals Make Human Gene Products
Human
gene
product will
be released
in milk
Applications of Biotechnology
Transgenic Animals as Models of Human Diseases
Transgenic
Mouse with
defective
human
hormone
gene
interfering
with growth
Same type
of mouse
“rescued”
by blocking
action of
human gene
Andrew Gobea
Gene Therapy
for SCID
Ex vivo:
Gene is
introduced
into cells
outside the
body
In vivo
Gene Therapy
Injection
of gene
Aerosol
spray
delivers
gene
Cystic Fibrosis
Blindness: Leber’s Congenital Amaurosis (LCA)