DNA fingerprinting

• When was DNA analysis first used in forensics?

  1980s
• What is karyotyping?

  The analysis of chromosomes in cells
• What is DNA fingerprinting?

  The pattern of DNA fragments obtained by examining a person's unique sequence of DNA base pairs
• What is nuclear DNA?

  DNA inherited from both parents, found on the chromosomes and is completely unique
• What is mitochondrial DNA?

  DNA found in the mitochondria of cells, inherited from the mother, not unique
• What are the 2 different sections of DNA?

  introns and exons
• What are exons?

  DNA that codes to make proteins and other molecules
• What are introns?

  DNA that does not produce proteins or other molecules
• What percentage of the genome in non-coding?

  98.5%
• Where is most of the variation in DNA found?

  Non-coding regions
• What are polymorphisms?

  The presence of variations in DNA sequences
• What does a DNA profile look like?

  A pattern of bands, depending on which section of DNA is being observed
• What are the 2 main methods of DNA profiling?

  • Variable number of tandem repeats (VNTR)
  • Short tandem repeats (STR)
• What are the steps of DNA fingerprinting?

  1. Extraction
  2. Digestion
  3. Separation
  4. Hybridisation
  5. Development
• What is amplification?

  Increasing the quantity of particular regions containing STRs using PCR and specific, fluorescently labelled primers
• What is separation?

  The DNA sections are separated using electrophoresis
• What is comparison?

  The DNA is compared to a sample under a UV light
• How long can a VNTR be?

  9-80 bases
• What are VNTRs?

  Repeating sections of DNA
• What is an STR?

  A sequence of DNA that repeats in the noncoding DNA
• How long are STRs?

  2-5 bases
• Which are quicker and easier to read between STRs and VNTRs?


  STRs
• What are the two main purposes of DNA profiles?

  • Tissue matching
  • Inheritance matching
• What is tissue matching?

  Where two sample of DNA are matched to the same person
• What is inheritance matching?

  Parts of one sample matches a relative, must follow the rules of inheritance
• How can sources of DNA be gathered?

  Blood, saliva, hair, skin cells
• What is a polymerase chain reaction?

  A technique that creates billions of copies of DNA samples for multiple tests and even modern tests years later
• What is the process of electrophoresis?

  • Pass an electric current through gel, causing DNA fragments to move from the negative to positive end
  • Special stains highlight sections of DNA
  • DNA probes cause some strands to glow and be identified under UV
• What is the main process of electrophoresis?

  Short bands of DNA move faster while longer bands move slower
• What does VNTR stand for?

  Variable number tandem repeats
• What is digestion?

  Restriction endonucleases cut DNA into restriction fragments
• What happens after the DNA has separated into bands?

  The gel is immersed in alkali to separate the double strands into single strands
• What is southern blotting?

  • A nylon membrane is laid over the gel
  • The membrane is covered with absobent paper, which draws up the liquid containing the DNA
  • Transfers DNA fragments to the nylon membrane in the relative positions they occupied on the gel
• What is hybridisation?

  Binding radioactive or fluorescent probes with the VNTRs
• How are the results of DNA fingerprinting interpreted?

  Examined through an automatic scanning machine where 2 sample are compared
• How can DNA fingerprinting be used in animal breeding?

  • Conservation
  • Prove the pedigree of an animal