Lecture 7: Genetic Analysis in Bacteria and Bacteriophages

• What are antibiotics?


  Chemicals that kill or inhibit the growth of bacteria

  
• What is the primary use of antibiotics?


  To treat bacterial infections
• Where are antibiotics produced in nature?


  By soil bacteria and fungi
• What was the first antibiotic discovered?

  Penicillin
• In what year was penicillin discovered?


  1929
• Which fungus produces penicillin?

  Penicillium
• How did penicillin revolutionize medicine?


  By providing an effective treatment for bacterial infections
• Who discovered penicillin?

  Alexander Fleming
• How do different antibiotics work against bacteria?


  They target different cellular processes to restrict bacterial growth
• What is a significant concern regarding antibiotics today?


  Antibiotic resistant bacteria are on the rise
• Name one antibiotic-resistant bacterium.

  Methicillin Resistant Staphylococcus aureus
• What is another example of an antibiotic-resistant bacterium?

  Vancomycin-Resistant Enterococci
• Name a third antibiotic-resistant bacterium.

  Fluoroquinoline-Resistant Pseudomonas aeruginosa

  
• What are the mechanisms of antibiotic resistance?


  • Don’t let it in!
  • Spit it out!
  • Break it!
  • Use something else!
  • Change yourself!
• How do bacteria become resistant to antibiotics?


  Through mutations in their genome
• How can antibiotic resistance be selected in bacteria?


  By growing soil samples where an antibiotic is the sole carbon source
• What does selection mean in the context of antibiotic resistance?


  A process that selects for a survivor/winner under environmental stress
• What happens to susceptible bacteria in the presence of antibiotics?


  They are killed by the environmental stress

  
• What do resistant survivors do after the stress of antibiotics?


  They re-establish the population
• What are the causes of antibiotic resistance selection?


  • Misuse of antibiotics
  • Prescribed when not relevant (e.g., for viral infections)
  • Treatment not followed to completion
  • Overuse in agriculture

  
• How does mutation contribute to antibiotic resistance?


  It is a slow route for developing resistance
• How can bacteria transfer genetic material to each other?


  Through direct contact or genetic transfer mechanisms
• What is the significance of genetic transfer in bacteria?


  It allows for rapid spread of antibiotic resistance genes
• What was demonstrated in 1946 regarding genetic transfer?


  Genetic transfer by bacterial conjugation
• Who won the Nobel Prize in Physiology or Medicine in 1958 for their work on genetic transfer?


  Joshua Lederberg and Edward Tatum
• What does the term "met+" indicate in the context of bacterial genetics?


  Growth without the amino acid methionine
• What does "bio+" signify in bacterial genetics?


  Growth without the nutrient biotin
• What does "thr+" represent in bacterial genetics?


  Growth without the amino acid threonine
• What does "leu+" indicate in bacterial genetics?


  Growth without the amino acid leucine
• What does "thi+" signify in bacterial genetics?


  Growth without the nutrient thiamine
• What happens when two bacterial strains are mixed in minimal media?


  No colonies grow without physical contact
• What is required for DNA transfer during conjugation?


  Interaction between bacterial cells through a pilus
• What is the F factor in bacterial conjugation?


  A fertility factor that confers the ability to donate DNA
• What do F+ cells contain?


  The F factor plasmid
• What do F- cells lack?


  The F factor plasmid
• What happens when an F- cell receives the F factor?


  It can act as a donor
• What are plasmids?


  Small circular pieces of DNA that replicate independently
• What do R plasmids confer?


  Antibiotic resistance
• What do col plasmids encode?


  Colicins that can kill neighboring bacteria
• What do virulence plasmids carry?


  Genes that turn bacteria into pathogenic strains