2. What is Gel Electrophoresis?
Gel electrophoresis is a
process that separates
fragments of DNA based on
their sizes.
3. Step 1
Place DNA into tubes
DNA can come
from tissue or
body fluid, such as
cheek cells, blood,
skin, and hair.
4. Step 2
Polymerase Chain Reaction
The polymerase chain
reaction uses a machine
called a thermocycler to
quickly copy a piece of
DNA.
Continue these
three steps 30 to
40 times to get lots
of copies of DNA.
5. Step 3
Place restriction enzymes into DNA
The restriction enzymes
cut the DNA into different
sizes according to it’s
sequence.
6. Step 4
Dye DNA and place into gel
The gel is made with
The gel is made out of wells at one end so
agarose, which is similar that the DNA can be
to jello. loaded into the gel.
7. Step 5
Run electric current through gel
DNA is negatively
charged so it will move
towards the positively
charged end of the gel.
8. Step 6
Smaller pieces of DNA travel farther than Larger
pieces of DNA
End result!
9. Gel Electrophoresis is used to...
Solve criminal cases
Solve paternity cases
Diagnose genetic diseases
Determine genetic kinship among species
10. Pros Cons
Easy to do Expensive
DNA does not get ruined in the Time consuming
process Uses hazardous material
You only need a small amount
of DNA to start with
DNA can be detected no matter
what size it is
11. Tommie Lee Andrews Case
Tommie Lee Andrews was the first person in the U.S
to be convicted with the help of DNA fingerprinting
evidence. Andrews was convicted for strangling two teenage
girls. The judge in Andrews’ first trial did not allow the DNA
fingerprinting evidence, although Andrews ended up having
a second trial. The judge in his second trial did allow the
DNA fingerprinting, which proved Andrews guilty and he
was convicted in 1987. This is just one of many cases that
DNA fingerprinting/gel electrophoresis has been used to
solve a crime.
