Biology 1001A Lecture Notes - Dna Profiling, Pyrimidine Dimer, Dna Repair
19 Nov 2012
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Document Summary
Characteristics of str loci that make them useful for forensic dna analysis (dna fingerprinting) Dna fingerprinting: unique combinations and variations of the dna sequence. Short tandem repeat (str) sequence: loci in noncoding region of genome; short sequence of. Dna repeated in series, with each repeat about 3 to 5 bp. Each locus has different repeated sequence and the number of repeats varies among individuals in a population. Mechanism of dna recombination: two molecules of dna with similar sequence are brought into close proximity. Homologous sequence of bases, allowing dna molecules to line up and recombine precisely: enzymes nick the dna backbones, exchange the ends, and reattach them. Covalent bond in each of the four sugar-phosphate backbones broken. Backbones are reattached to another dna molecule: final result is two recombined dna molecules. Cutting and pasting four dna backbones results in one recombination event. Chromatids of homologous chromosomes undergo recombination by exchanging segments while paired.
