DNA Fingerprinting Catherine S. Quist

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.

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

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

Restriction Enzyme Cuts Yield Different Sized DNA Fragments 11 10 2

Gel Electrophoresis is Used to Separate the Fragments Based on Size

Gel Animation http://www.slic2.wsu.edu:82/hurlbert/micro101/pages/Chap10.html

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.

Different People Have Different Restriction Enzyme Cut Sites 1 2 Resulting in different band patterns on a gel. Resulting in different sized DNA fragments.

Solving a Murder Mystery Using DNA Fingerprinting Who did it?

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.