Lab 13

• Bacterial Conjugation


  Transfer of genetic material from a donor bacterium to a recipient bacterium by direct contact between two bacterial cells
• Asexual reproduction in bacteria


  • Binary fission
  • Vertical transfer of genes from one generation to the next
  • Does not offer genetic diversity
• Lateral transfer of genes among bacterial cells


  • Provides a way to increase genetic diversity
• Methods of genetic material transfer in bacteria


  • Soluble DNA transfer (transformation)
  • Via bacteriophage (transduction)
  • Direct contact between two bacterial cells (conjugation)
• Traits acquired by recipient bacteria


  • Virulence factors
  • Resistance factors
  • Additional metabolic abilities
• Plasmid


  Extrachromosomal circular piece of DNA with its own origin of replication
• Fertility plasmid (F plasmid)


  Carries a gene that codes for pilus
• F+ cell


  Donor cell that possesses a fertility plasmid
• 1. cell


  Recipient cell that lacks the fertility plasmid
• Bacterial conjugation


  1. F+ cell attaches to F- cell via pilus

  2. Transfer of DNA from donor to recipient
• Incubation temperature for control plates should be 37°C
• Conjugation experiment


  1. Mix 0.1ml of F+ strain and 0.9ml of F- strain

  2. Incubate mixture at 37°C for at least 2 hours

  3. Spread 0.1ml of mixture on ampicillin + streptomycin plate
• The purpose of spreading the mixture on the ampicillin + streptomycin plate is to check for successful conjugation by looking for recombinants resistant to both antibiotics