Genetic screening

• What is a DNA probe?

  A single-stranded piece of DNA
• What is DNA hybridisation?

  A DNA probe attaches to a complementary sequence
• What enzymes makes DNA fragments for DNA probes?

  Restriction endonuclease, reverse transcriptase or gene machine
• What are the two ways to label a DNA probe?

  Fluorescently and radioactively
• What does it mean if a DNA probe glows?

  DNA hybridization occurs and the gene is present
• How are DNA probes replicated?

  Via PCR
• What are the steps in using DNA probes after PCR?

  • Heat DNA samples
  • Add probes and cool mixture
  • Wash the sample
  • Check for probe attachment
• What does genetic counseling involve?

  Talking to a specialist about a positive result
• What does genetic counseling inform patients about?

  Heritable disorders and their effects
• What is personalised medicine?

  Targeted drugs to treat a heritable disorder
• When are personalised medicines given?

  After screening
• What are the positives of genetic screening?

  • Make informed reproductive choices
  • Make informed lifestyle choices
  • Identify conditions early for personalized treatment
• What are the negatives of genetic screening?

  • May cause depression
  • Increased costs of health/life insurance
  • Can cause pressure to abort
• What are VNTRs?

  Variable number of tandem repeats
• Why can the number of repeats in VNTRs vary?

  Non-coding sequences are not affected by selection
• What are the steps to isolate non-coding regions?

  • Collect DNA fragment
  • Use PCR to amplify fragment
  • Use restriction endonuclease to cut out non-coding sequences
• What can scientists identify by comparing banding patterns from non-coding regions?

  The relationship between organisms
• What are the steps of gel electrophoresis?

  • Add samples to wells
  • Apply voltage to gel
  • Fragments spread down forming bands
  • Transfer bands to paper
  • Add DNA probes with stain
  • Take photo
• How does VNTR length affect its movement in gel electrophoresis?

  The shorter the VNTR the further it moves
• What types of molecules can be investigated using gel electrophoresis?

  RNA, DNA and proteins
• What is the purpose of using DNA probes with stain in gel electrophoresis?

  To make bands easier to see