Lab Notes and Procedures-12 Biology 1004

North Arkansas College

Topic:  DNA Fingerprinting in Forensic and Paternity Cases

1. DNA fingerprinting (or typing) allows for identification of sources of DNA.
2. Method has become very important in providing evidence for paternity and criminal cases.
3. Blood typing can only exclude a suspect, whereas DNA fingerprinting can provide possible identification with great accuracy.
4. DNA fingerprinting involves the electrophoretic analysis of DNA fragments generated by restriction endonucleases.
5. Restriction endonucleases cut DNA within the strands at specific recognition sites.
6. Most recognition sites are 4-8 bases long.
7. Agarose gel electrophoresis is a procedure used to analyze DNA fragments generated by restriction endonucleases. Agarose contains tiny pores that act as a sieve to separate DNA on basis of size.
8. DNA samples are loaded into wells on the agarose gel. DNA has a strong negative charge and migrates toward the positive pole in an electrical field.
9. DNA fragments are separated on the basis of size and charge.
10. DNA fragments can be visualized as bands on the agarose gel using methylene blue or ethidium bromide.
11. No 2 individuals have exactly the same restriction enzyme recognition sites or bands exhibited on the agarose gels.
12. For paternity testing, we look for the differences in mother and child's DNA pattern. The biological father's DNA will contain DNA fragments found in child's, but not mother's DNA.
13. In criminal cases, we look for bands of crime scene DNA that match a suspect's DNA.

Run 2 sets of agarose gels with the following DNA samples:

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