FORENSIC SCIENCE DNA

1. FORENSIC SCIENCE DNA Unit 3A Day Four

2. You should have back: • Isolating your DNA lab- 15 points • DNA Scavenger Hunt- 35 points • DNA extraction quiz- stamped • Serology Performance Assessment- 65 points • Serology TEST- 100 points

3. Due today: • You are Not the Mother case study • DNA fingerprint Virtual Activity • Serology test data analysis • TODAY’S ASSIGNMENTS: • PCR animation: on front table • Activity 7-4: on front table

4. Forensic Files, 3-26 • Is it possible for the DNA from two different people to match? • Justify your answer.

5. PCR--Polymerase Chain Reaction PCR is a technique for making many copies of a defined segment of a DNA molecule. It looks at six different inherited traits, each controlled by a specific gene.

7. PCR--Polymerase Chain Reaction The outcome is a doubling of the number DNA strands. Heating, cooling, and strand rebuilding is repeated typically 25 to 30 times, yielding more than one million copies of the original DNA molecule. Each cycle takes less than two minutes from start to finish.

8. PCR--Polymerase Chain Reaction • Heat the DNA strands to 94 degrees which causes the strands to separate (unzip). • Add primers to the separated strands. • The primers combine with the DNA strands. • Add DNA polymerase and a mixture of free nucleotides to the separated strands. • The tube is cooled down to 72 degrees which results in the rebuilding of a double-strand of DNA.

9. Advantages of PCR • Minute amounts of DNA template may be used from as little as a single cell. • DNA degraded to fragments only a few hundred base pairs in length can serve as effective templates for amplification. • Large numbers of copies of specific DNA sequences can be amplified simultaneously with multiplex PCR reactions. • Commercial kits are now available for easy PCR reaction setup and amplification. Problem: Contaminant DNA, such as fungal and bacterial sources, will not amplify because human-specific primers are used.