DNA FINGERPRINTING

1. What do you think DNA fingerprinting is?

2. What do you think DNA fingerprinting can be used for?

Background:

• Term DNA fingerprint coined by British geneticist in 1985

• A DNA fingerprint is a unique picture of part of a person’s DNA.

• Each person will have a different DNA fingerprint.

• Closely related individuals will have closely related DNA fingerprints

Why is this possible?

• There are regions in the DNA that are known to have differences in every individual.

• By examining these areas can get a unique picture of that person’s DNA.

• Comparing the pictures can then show how closely related people are.

Steps to make a DNA fingerprint:

1. Isolate the DNA– From cells/tissues– Blood, hair, skin, saliva

2. If necessary, increase the amount of DNA – Use PCR (polymerase chain reaction)

which causes the DNA to replicate itself quickly. Done by heating and cooling a mixture of DNA and DNA polymerase

3. Cut the DNA into fragments– Use restriction enzyme to cut it into chunks.

These chunks are called RFLP’s – Restriction Fragment Length Polymorphs

4. Use gel electrophoresis to sort the fragments by length. – DNA is added to a gel.– Apply electrical current– DNA moves different distances bases on size – Long RFLPs move slow and short ones move

faster through the gel

5. Stain the DNA to see distance each fragment traveled

Or

Transfer the DNA to a nylon sheet and use a radioactive probe to mark certain areas on the DNA.

6. Either way – a pattern is produced which is unique to that individual.

7. DNA fingerprint is now ready for analysis by comparing it to known sequences.

Uses for DNA Fingerprints:

1. Diagnosis of Inherited Disorders

2. Developing cures for Inherited Disorder

3. Biological Evidence– Crime scene– Establish paternity

Uses (cont)

4. Personal Identification– Military– Missing Persons– Disasters– Refugees– Adoption

Uses (cont.)

5. Poaching

6. Identification of new species

7. Determining evolutionary relationships