Polymerase Chain Reaction - Creates many copies of a fragment of DNA - Allows for multiple testing of same strand of DNA - Useful in forensic science
1. Heat DNA to denature it (DNA uncoils) 2. Expose to a heat resistant polymerase, primers and DNA nucleotide 3. Polymerase copies DNA 4. Allow to cool (DNA re-anneals: reforms) 5. Repeat cycle many times
Recognize a specific sequence in DNA and cleave at that sequence - Because patterns will show up in difference places in different DNA sequences (sequences are unique in an individual) will end up with different lengths of fragments
- DNA is slightly negative - Has been cut into different length fragments by restriction enzymes - Wells are cut into the gel: DNA is placed in wells - Electric current is applied to the gel to pull DNA pieces through to positive end
Bands on Gel
- Smaller DNA segments move farther - The closer the restriction enzyme sites, the shorter the resulting fragment - Can help to determine a pattern of restriction enzyme sites in DNA - Certain sequences (fragment lengths) will be passed by 1 parent
1. Restriction enzymes are used to cut up sample of DNA 2. DNA is compared to other DNA to find match(culprit, suspect) or similarity(parent, child) 3. PCR allows really small samples of DNA to be used in fingerprinting (nucleotides and enzymes)
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