1. DNA Fingerprinting
Catherine S. Quist

2. LEGO Model of DNA DNA is a molecule in your body.
It is a code, which stores instructions for building the “machines” in your body.
It is a double helix.
It is a millionth of a millimeter wide.
In humans, a molecule of DNA is 200,000,000 bases long.

3. DNA is a Code GGAAAACTAAC CCTTTTGATTG
The genetic code is written in A’s, T’s, C’s and G’s.
The sequence of A’s, T’s, C’s and G’s uniquely identifies a person, unless they are a twin.
That’s why it’s called DNA fingerprinting.
GGAAAACTAAC
CCTTTTGATTG

4. Restriction Enzymes are Molecules that Cut DNA at Particular “Words”

5. Restriction Enzyme Cuts Yield Different Sized DNA Fragments11 10 2

6. Gel Electrophoresis is Used to Separate the Fragments Based on Size

7. Gel Animation

8. Example DNA Fingerprint
Column in Gel corresponds to a person’s DNA.
It is called a person’s DNA fingerprint.
Row corresponds to DNA fragment size.

9. Different People Have Different Restriction Enzyme Cut Sites1 2
Resulting in different band patterns on a gel.
Resulting in different sized DNA fragments.

10. Solving a Murder Mystery Using DNA Fingerprinting
Who did it?

11. Solving Our Murder Mystery Using DNA Fingerprinting
Given crime scene DNA and suspect DNA you will construct a gel.
You will then analyze the gel to find a match between the crime scene DNA and a suspect’s DNA.
You will use this information to make inferences about the murders.