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Restriction Enzymes and DNA Fingerprinting. Molecular Scissors for Cutting DNA Precisely. Its because of these biological catalysts that genetic engineering is possible Restriction enzymes can also be called Endonucleases . Types of Restriction Enzymes. Type I
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Molecular Scissors for Cutting DNA Precisely • Its because of these biological catalysts that genetic engineering is possible • Restriction enzymes can also be called Endonucleases
Types of Restriction Enzymes • Type I • Binds to the recognition site and then cut randomly somewhere along the length of the molecule • Type II • Binds to the recognition site and then cleaves the molecule by clipping the DNA backbones particular DNA molecule with a particular restriction enzyme will always produce the same set of DNA fragment • Type III and Type IV
Types of Cuts • Blunt end Cutters • Sticky-end Over-hangers
Uses • Restriction enzymes can be used in processes such as… • Southern Blotting • Cloning Verification • And Forensic DNA Fingerprinting
Southern Blotting • 1st step of Southern Blotting is digestion of DNA where the restriction enzymes come in • Hind III was the restriction enzyme used to cut up the DNA • Hind III comes from Haemophilus influenzae Rd
Genomic DNA digestion and Southern Blots UC C UC C UC C
Eco RI or Escherichia coli RY 13 was used Cloning Verification
Forensic DNA Fingerprinting • Was first described in 1985 by geneticist Alec Jeffreys who discovered • That some sections of DNA contain DNA sequences that were repeated over and over again • The number of repeated sequences vary from individual to individual • Dr. Jeffreys also created the technique known as restriction fragment length polymorphism (RFLP) to examine the length variation of these DNA repeat sequences
VNTRs and STRs • VNTRs (variable number of tandem repeats) and STRs (short tandem repeats) are DNA repeating sequences • VNTRs are also known as minisatellites which range from 10-100 bases in length • STRs are also known as microsatellites which range from 2-6 bases
STRs and Forensic Fingerprinting • The small size of STRs are better suited for use in forensic applications where degraded DNA is common • In 1997 13 core STR loci were chosen to be the basis of CODIS (Combined DNA Index System) • CSF1PO, FGA,TH01, TPOX, VWA, D3S1358, D8S1179, D13S317, D16S539, D18S51, AND D21S11 • PE Applied Biosystems and Promega Corp. produce STR kits