Bacteria Notes

Bacterial Transformation and Transduction

  • Transformation: Bacteria take up DNA fragments (plasmids) from their environment.

    • Lab example: Weakening bacterial cell walls with fulcate chloride allows plasmid uptake.

  • Transduction: Genetic material transfer via viruses.

    • Virus injects DNA into bacteria, mixes with bacterial chromosome.
    • New viruses assemble with combined bacterial and viral DNA.
    • These viruses infect new cells, introducing bacterial DNA.

Genetic Recombination

  • Ways bacteria mix genes, not sexual reproduction, but mix genetic information from other bacteria.
  • Otherwise, bacteria create clones of themselves through migration.

Bacteria and Disease

  • Only about 1% of bacteria are pathogenic (disease-causing).
  • Many bacteria are beneficial (e.g., gut bacteria, sewage treatment, food production).
  • Some bacteria fix nitrogen (create nitrates and nitrites) or act as decomposers.

Antibiotics

  • Chemicals that kill bacteria; our main defense against disease-causing bacteria.
  • Mechanisms:
    • Prevent cell wall formation during binary fission.
    • Prevent DNA synthesis, hindering reproduction.
    • Prevent protein synthesis, impairing survival.
    • Block important enzymes.
    • Interfere with peptidoglycan in the cell wall.

Discovery of Penicillin

  • Alexander Fleming discovered penicillin accidentally.
  • Mold contaminated a petri dish, inhibiting bacteria growth.
  • The mold secreted penicillin, which interferes with bacterial peptidoglycan cell walls.

Antibiotic Resistance

  • Over-prescription led to increased antibiotic resistance by bacteria.
  • Bacteria with mutations survive and reproduce, passing on resistance.
  • Important:
    • Only take antibiotics when prescribed for bacterial infections.
    • Complete the full course of antibiotics to kill as many bacteria as possible.
    • Stopping early leaves resistant bacteria that can spread resistance.

Antibiotics Side Effects

  • Antibiotics kill both harmful and beneficial bacteria.
  • Can cause stomachaches (kills good gut bacteria).
  • Can lead to yeast infections (disrupts reproductive organ bacteria balance).

Famous Bacteria

  • Anthrax: Caused by inhalation of spores.
  • Bubonic Plague and Cholera: Largely eradicated due to antibiotics.
  • Tuberculosis (TB): Rising in antibiotic resistance.
  • Typhus: Caused by fleas or lice bites; preventable with hygiene.