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Biotechnology
Altering an organism's genetic code so that it produces desired protein
B. Techniques to Locate and Identify DNA
1. DNA Extraction
2. Restriction Enzymes- enzymes that cut DNA at a specific base sequence
Restriction Enzymes
Contributions of Salvador Luria
Early biochemistry work was conducted on organisms with small genomes like E. coli and viruses that prey upon them
A plate with nutrient agar would be inoculated with bacteria and they would be allowed to grow until they covered the plate
Later, phages were added and they would attack and kill the bacteria leaving empty spots on the plate called plaques
Salvador Luria’s Observation and Hypothesis
• Luria observed some bacteria that were unaffected when exposed to phages
• Luria hypothesized that these bacteria had some type of primitive immune system that restricted phage growth
• Contributions of Daniel Nathans He realized because DNA has a negative charge, restriction fragments could be separated using an electric current
Phage
Host Cell DNA
Host Cell
Restriction Enzyme
Viral DNA
Bacteria Evolved Restriction Enzymes
In order to reproduce, viruses must attach to a host cell
The virus then injects it’s DNA into the host cell
How Restriction Enzymes Protect Bacteria
Restriction enzymes bind with the viral DNA at specific base sequences called recognition sites
The viral DNA is cut at specific sites called restriction sites which destroys it and protects the bacteria from infection
Naming Restriction Enzymes
EcoR I
E genus Echericia
Co species coli
R Strain R
I Order found 1st
BamH I
B genus Bacillus
am species amyloliquefaciens
H Strain H
I Order found 1st
Hind III
H genus Haemophilous
in species influenzea
d Strain d
III Order found 3rd
3. Gel Electrophoresis- separating cut DNA fragments by size using an electric current
4. PCR- Polymerase Chain Reaction- allows specific DNA fragments to be copied millions of times
5. RFLPs- Restriction Fragment Length Polymorphism
a) Used to identify DNA when a mutation adds or deletes a restriction site
b) Gel electrophoresis separates the DNA fragments and mutations are identified by an abnormal number of fragments
6. VNTRs & STRPs- similar to RFLP analysis, but uses highly variable, non-coding sequences of DNA
C. Techniques for Inserting DNA1. Heat Shock Transformation- rapid temperature fluctuation of cell walls that pushes DNA into a bacterial cell
2. Microinjection- thin needles insert DNA into cells
D. Uses of Recombinant DNA Technology
1) Pharmaceuticals- Humilin, TPA, interferon, TNF, Artificial hemoglobin, human growth hormone
2) Agriculture- incide, Flavr-saver tomatoes, frost resistance, salt resistance, insect resistance, herbicide resistance, nitrogen fixation
3) Forensics- DNA finger printing
4) Medical- gene therapy
E. Dangers of Genetic Engineering
1. Pathogens- disease causing organisms
2. Eugenics- should we control or alter our own genome?
3. Stem Cells- growing new human tissues from cell derived from fertilized eggs
4. Legal Questions- can/should we patent life?
5. Genetic Screening- who would get the results of the tests and how could test
results be used?
6. GMOs- Genetically modified organisms