Microbiology Mid-term 1

  1. explain: RNA world hypothesis
    1986 - W. Gilbert

    • The earliest cells may have beenRNA surrounded by liposomes.Why RNA?... because…
    • 1.Some RNA molecules (ribozymes) can form peptide bonds (protein function)
    • 2.RNA molecules can replicate (hereditary function)
  2. Define: endocytosis hypothesis
    Plasma membrane extended inwards(endocytosis) and surrounded the nuclear region.
  3. explain: endosymbiotic hypothesis
    Mitochondria and Chloroplasts of eukaryotes originated from ingested prokaryotes.
  4. How did Cellular Microbes evolve?
    • Mutation of genetic material led to selected traits.
    • New genes and genotypes evolved
    • Bacteria and Archaea increase genetic pool by horizontal gene transfer within the same generation
  5. How do we classify microbial diversity?
    • Taxonomy: Science of biological classification. It consists of:
    • •Classification: Arrangement of organisms into groups or Taxa, based upon evolutionary relatedness.
    • •Nomenclature: Assignment of names to taxonomic groups
    • .•Identification: determining if a particular isolate belongs to a recognized taxon.
  6. Species (Domain Eukarya):
    Interbreeding population of organisms that are repoductively separated from other groups.
  7. Species: (Domain Bacteria and Archaea):
    Collection of strains that share stable properties and differ significantly from other groups of strains.
  8. Strains:
    Descendants of a single, pure microbial culture.
  9. Sterilization:
    Removalof all living cells, spores, acellularentities froman object; e.g., autoclaving of microbiological culture media.
  10. Desinfection:
    Removal of all potential pathogens from an object. Non-pathogenicviable spores may remain; e.g., boiling water, pasteurization of milk and juices.
  11. Sanitization:
    Reductionof microbial population to safe levels; e.g.,householdcleaners.
  12. Antisepsis:
    Removal /reduction of microbes outside the body; e.g., alcohol swaps.
  13. Chemotherapy (chemical)
    Removal/reductionof pathogenic microbes inside the body;e.g.,antibiotics.
  14. Mode of action: of Autoclave (physical)
    Protein Denaturation
  15. Mode of action: Dry heat incineration (physical)
    cell denaturation
  16. Mode of action: Ionizing radiation (physical)
    DNA damage
  17. Mode of action: Membrane filters (mechanical)
    physical seperation
  18. Mode of action: Ethylene oxide (chemical)
    denatures DNA and inactivates proteins
  19. Mode of action: Phenolics (chemical agent)
    block bacterial fatty acid synthesis
  20. Mode of action: Alcohols (chemical agent)
    denature proteins and dissolve membrane lipids
  21. Mode of action: Halogens (chemical agent)
    oxidizing agent - denatures proteins
Card Set
Microbiology Mid-term 1
Will be on mid-term 1