Manipulating Genomes

• What is DNA sequencing?

  Identifying the base sequence of DNA
• How have sequencing methods changed over time?

  They have become automated and can read genomes
• What are the benefits of genome-wide comparisons?

  • Determine evolutionary relationships between species
  • Tailor medical treatment to individuals of the same species
• How can DNA sequencing be used in synthetic biology?

  It predicts amino acid sequences from genes
• What is DNA profiling?

  Identifying unique areas of a person's DNA
• What are the uses of DNA profiling?

  • Forensics: Compare DNA from crime scenes
  • Medicine: Screen for heritable diseases
• How can we amplify DNA fragments for sequencing?

  Using the polymerase chain reaction (PCR)
• What does the reaction mixture in the first stage of PCR contain?

  DNA fragment, primers, free nucleotides, DNA polymerase
• What is the process of amplifying DNA fragments using PCR?


  1. Heat to break DNA strands
  2. Cool to allow primers to bind
  3. Heat to activate DNA polymerase
  4. New DNA acts as template for next cycle
• How is gel electrophoresis used in DNA profiling?

  • DNA fragments placed in gel
  • Electric current applied; fragments move
  • Shorter fragments travel further, creating unique patterns
• What is meant by genetic engineering?

  Inserting DNA from one organism into another
• What is the process of isolating a DNA fragment?

  • Restriction enzymes cut DNA at specific sequences
  • Different enzymes cut at different points
  • Specific enzymes allow cutting out a gene of interest
• What is the process of inserting a DNA fragment into a vector?

  • Use a plasmid as the vector
  • Cut plasmid with the same restriction enzymes
  • DNA ligase joins the fragment and plasmid
• What is the process of inserting a vector into a host cell?

  • Mix host cells with vectors in ice-cold solution
  • Shock to increase cell membrane permeability
  • Encourages cells to take up vectors
• What are some ethical issues around genetic engineering?

  • Insect resistance in crops
  • GE animals for pharmaceuticals (pharming)
  • GE pathogens for research
  • Access to GE seeds for poorer farmers
• What is gene therapy?

  Replacing a faulty allele with a normal allele
• Differentiate between somatic gene therapy and germ line gene therapy.

  • Somatic: allele introduced to target cells only; short-term
  • Germ line: allele introduced to embryonic cells; permanent