Operons and Horizontal Gene Transfer

• Repressor and corepressor are relevant to the trp operon?
• Inducer and repressor is/are relevant to the lac operon?
• RNA polymerase binds to the promoter region. In bacteria this is at the -35 region.
• RNA polymerase and Corepressor are relevant to the tryptophan operon?
• Tryptophan can act as a corepressor by binding to the repressor
• Tryptophan is an amino acid.
• In the presence of lactose, bacteria produce ß-Galactosidase so the repressor won't bind.
• An operon is series of genes under the control of a single promoter.
• Transduction is when

  Transfer is performed by viruses and phages
• Conjugation is when a


  Plasmid is transferred via a F pilus
• Transformation is when


  Naked DNA is taken up by bacteria
• Beta-galactosidase can only be made

  if glucose is absent.
• If synthesis of their repressors stopped, lac & trp operons won't work.
• Permease allows beta-galactosidase into the cell. True or False

  False
• Gene expression is RNA being made (copied) from DNA
• Bacteria do not want to induce the lac operon in the absence of lactose because it would be a waste of resources/energy
• When tryptophan is present the cell doesn't want to use energy and resources to make more
• An operon only works when glucose is absent and lactose is present
• If cAMP is high, glucose is low
• If glucose levels are high, cAMP levels are low
• cAMP binds to the CAP protein
• When glucose is absent and lactose is present the lac repressor binds to the operator region and blocks RNA polymerase from making genes
• When glucose is present and lactose is absent, the CAP protein can't bind to the CAP site
• When glucose is present and lactose is present, the CAP protein can't bind to the CAP site and AL lactose prevents the lac repressor from binding to the operator
• When glucose is absent and lactose is present the cells will want to transcribe genes
• A streptococcus pneumoniae smooth strain

  • Has a capsule
  • Is virulent
• Virulent means


  Able to cause disease
• A streptococcus pneumoniae rough strain

  • Has no capsule
  • Is avirulent