1. Biogenetic Engineering

2. PCR • Polymerase Chain Reaction (PCR) • ·PCR is the cloning of DNA (amplification) • ·Amount of DNA can be increased rapidly • ·Useful if the source of DNA is small • ·Temperature is used instead of enzymes (helicase) to separate the DNA strands • ·Taqpolymerase is thermostable (not denatured by the heat) and is still able to add new nucleotides to the parent strands • ·This is an automated process that requires specialized machines called ‘Thermocyclers”

3. 3 Steps to PCR • Denature: Heat the solution containing the Taq polymerase, DNA and nucleotides to separate the double-stranded DNA into single strands • Anneal: Cool the solution so primers can attach to the exposed complementary nucleotides on the single stranded DNA • Extend: Once primers have attached to DNA, Taq polymerase adds nucleotides to both exposed primed DNA strands. • Process is repeated many times…millions of copies in just hours

4. Animation: http://www.dnai.org/b/index.html Click techniques, then amplifying, then PCR animation

5. Gel Electrophoresis • ·Agar gel with rectangular indentations called “wells” at one end between a positive and negative electrode. • ·DNA that has been cut into fragments (by an enzyme) is mixed into a solution with dye and then placed into one of the wells • ·An electrical current is passed across the gel.

6. Gel Electrophoresis • ·DNA fragments are separated based on their size (how many base pairs long they are) and charge • ·Since DNA is a negatively charged molecule all of the fragments will move towards the positive electrode (which is why the wells are always located nearest the negative electrode) • - Smaller fragments are the easier to move through the gel and therefore will move more quickly to the right. • - Large fragments move more slowly.

7. ·The picture below is of a gel after the DNA has been separated • ·Shows 6 separate samples of DNA • ·Each band corresponds to a group of DNA molecules of the same size • ·Samples b and c are identical and must therefore be from the same person

8. Uses • Gel electrophoresis is used for DNA profiling • ·Satellite (Tandem repeating) DNA are highly repetitive sequences of DNA from the non coding region of DNA. • ·Different individuals have a unique length to their satellite regions. • ·These can be used to differentiate between one individual and another. • ·There are different types of 'DNA fingerprinting' for different circumstance • - Forensic crime investigations • - Parentage Issues • - Animal breeding pedigrees • - Disease detection

9. ·Bands from different samples of DNA are compared to see if they match up • ·In the case of forensic investigations, one sample would be from the crime scene, one from the victim, and one from the suspect • ·If the bands match perfectly the suspect can be linked to the crime scene • ·In the case to the right suspect #1 appears to have been at the crime scene (must still be proven by law to have committed the crime)

10. ·In the case of paternity suits a sample of the child’s DNA, the mother’s DNA, and any potential father’s DNA is compared • ·About half of the bands in the child’s DNA sample will match with the mother • ·If the other half match with that of the third sample, the male is the father • ·In the example to the right Male #1 is the father • paternity animation • http://www.sumanasinc.com/webcontent/animations/content/paternitytesting.html