Genetic Engineering
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Transcript Genetic Engineering
DNA Fingerprinting
Comparing DNA samples
using gel electrophoresis
How is DNA fingerprinting
technology useful?
Food identification
Mystery meat
Endangered species
Forensics
Crime scenes
Overturning erroneous convictions
Human remains
Paternity/maternity
Child support
Immigration
Health and medicine
Genetic disorders
Bone marrow transplants
Identifying pathogens
How can we examine
DNA to look for
similarities and
differences?
Electrophoresis
“carry with electricity”
DNA samples
from crime
scene and
suspects
Bacteria provide
tools to cut DNA
“DNA scissors” produced by bacteria
Adaptation to protect bacteria against viruses
Restriction Enzymes
More than 3000 known restriction enzymes,
or “endonucleases”
Each cuts at a specific DNA sequence called
a restriction site.
Restriction sites are palindromes
How do restriction enzymes
work?
What happens when we cut all
DNA samples with the same
restriction enzyme?
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3
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-------------GAATTC-------------------------------GAATTC--------------------GAATTC---------GAATTC----GAATTC----GAATTC-----------------------------------GAATTC------------1 -------------GA ATTC----------------------------2 ---GA ATTC--------------------GA ATTC------3 ---GA ATTC----GA ATTC----GA ATTC------4 ---------------------------------GA ATTC---------
Electrophoresis animation
Click here
How will the fragments appear
in a gel?
1 -------------GA ATTC----------------------------2 ---GA ATTC--------------------GA ATTC------3 ---GA ATTC----GA ATTC----GA ATTC------4 ---------------------------------GA ATTC---------
Electrophoresis Procedure
Cut DNA samples with restriction enzymes
Add loading dye to samples
Load samples in gel and apply charge
DNA separates by size (small=fast)
Stain DNA in the gel
Bands appear where same-sized
fragments are located, forming a pattern
Compare patterns to find matches
Pipette technique
•Find well opening with tip
•Depress plunger s..l..o..w..l..y…
•Watch for air bubbles
•New tip for each sample!
The disposable graduated pipette