Gel electrophoresis power point may 23
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Transcript of Gel electrophoresis power point may 23
Ellie Landis
What is Gel Electrophoresis?
Gel electrophoresis is a process that separates
fragments of DNA based on their sizes.
Step 1Place DNA into tubes
DNA can come from tissue or
body fluid, such as cheek cells, blood, skin, and
hair.
Step 2Polymerase 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.
Step 3Place restriction enzymes into DNA
The restriction enzymes cut the DNA
into different sizes according to it’s
sequence.
Step 4Dye DNA and place into gel
The gel is made out of agarose, which is similar to jello.
The gel is made with wells at one end so that the
DNA can be loaded into the gel.
Step 5Run electric current through gel
DNA is negatively charged so it will move towards the positively charged
end of the gel.
Step 6Smaller pieces of DNA travel farther than
Larger pieces of DNA
End result!
Gel Electrophoresis is used to...
Solve criminal casesSolve paternity casesDiagnose genetic diseasesDetermine genetic kinship among species
Pros ConsEasy to doDNA does not get ruined in
the processYou only need a small
amount of DNA to start with
DNA can be detected no matter what size it is
ExpensiveTime consumingUses hazardous material
Tommie Lee Andrews CaseTommie 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.