Prokaryotes

• Equation for the breakdown of lactose by lactase


  lactose -> glucose + galactose
• What causes intolerance?

  Lacking an enzyme that breaks down a molecule ie lactose intolerant people lack the lactase enzyme
• What enzyme that breaks down lactose is found in bacteria?

  Beta galactosidase.

  • bacteria need to break down lactose to produce glucose to use in respiration
• What is the promotor region?

  Region before a gene found in both eukaryotes and prokaryotes where RNA polymerase binds.
• What is the operator region?

  Only found in prokaryotes- where the repressor protein is found
• What happens when lactose is absent?

  Repressor protein prevents RNA polymerase from binding to the operator region.

  • the gene is switched off
• What happens when lactose is present?

  1. Lactose binds to the repressor protein
  2. this changes the shape of the protein.
  3. this removes the repressor protein from the operator region.
  4. RNA polymerase binds to the promotr region.
  5. mRNA is made/ genes are transcribed.