STR Amplification

View mindmap
  • STR Amplification
    • What are STRs?
      • Short Tandem Repeats
        • Non-Coding repeating Sequences
          • Found on a location of the chromosome
        • Contain alleles
          • One from each parent
      • Can help identify people as they are highly discriminative
      • A large number of STR loci have been identified, but only around 20 are commonly analysed in forensic casework
    • What is STR amplification?
      • A simultaneous amplification of more than one locus
        • STR Interpretation
          • The dyes used to label the PCR products overlap and the raw data contains peaks that are composed of more than one dye colour
            • Software used, calculates how much spectral overlap there is between each dye and subtracts this from the peaks within the profile
              • DNA fragments are sized and genotypes are assigned
        • STR polymorphism detection
          • After STR polymorphisms have been amplified during PCR, the length of the products must be precisely measured.
            • This is done during electrophoresis
              • Electrophoresis separates DNA molecules depending on their lengths
                • Dyes can be used
    • Structure of an STR
      • Contain a core repeat region between 1bp and 6bp long and have alleles that are generally less than 350bp
    • First used in the early 1990s.
      • The UK Forensic Science Service developed the first STR-based typing system that was designed for forensic analysis in 1994
    • Advantages of STRs
      • Easily amplified by PCR and are suitable for degraded samples
      • Highly vairable
      • Commerical kits available which allows for multiplexing and standardisation
      • Uniform set of core STR loci - creating national and international sharing of profiles
    • Disadvantages of STRs
      • Wide use of commercial kits means that the choice of STRs is restricted
        • Not always useful for non European populations
          • Creates bias


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Genetics resources »