DNA profiling

• intron 


  DNA that does not code for protein
• exon 


  DNA that codes for protein
• STR

  short DNA sequences which are repeated many times
• Homologous chromosomes

  a pair of chromosomes

  1 paternal

  1 maternal
• restriction endonuclease

  enzymes that cut DNA at specific base sequences
• PCR

  technique used used to increase amount of DNA by using heat cycling
• DNA profiling

  take cheek swab

  bone marrow from skeleton

  finger prints dental profiles
• DNA profiling relies on the fact that everyone has unique DNA
• about introns

  within introns there are STR

  STR can have 2 to 50 base pairs

  STR can be repeated from 5 to several hundred times
• same STR can occur at the same locus on both chromosomes of a homologous pair but the number of repeats on each pair can be different
• how is DNA profile made

  DNA extracted from tissue sample

  fragments of different lengths made

  fragments are separated and visualised

  comparison made with reference DNA profile
• Creating fragments

  restriction endonuclease cut DNA at specific base sequences

  can be used to cut out STR sequences
• cutting DNA can have 2 results

  can produce blunt ends

  can produce sticky ends
• Steps of PCR

  90 degrees- 2 DNA strands separate

  55 degrees- primers anneal to the strands

  72 degrees- taq DNA polymerase attaches and synthesises new DNA strand
• primers 


  short sequences of DNA
• taq DNA polymerase

  do not denature at high temperatures