Microbiology Mid-term 1
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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)
Define: endocytosis hypothesis
Plasma membrane extended inwards(endocytosis) and surrounded the nuclear region.
explain: endosymbiotic hypothesis
Mitochondria and Chloroplasts of eukaryotes originated from ingested prokaryotes.
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
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.
Species (Domain Eukarya):
Interbreeding population of organisms that are repoductively separated from other groups.
Species: (Domain Bacteria and Archaea):
Collection of strains that share stable properties and differ significantly from other groups of strains.
Descendants of a single, pure microbial culture.
Removalof all living cells, spores, acellularentities froman object; e.g., autoclaving of microbiological culture media.
Removal of all potential pathogens from an object. Non-pathogenicviable spores may remain; e.g., boiling water, pasteurization of milk and juices.
Reductionof microbial population to safe levels; e.g.,householdcleaners.
Removal /reduction of microbes outside the body; e.g., alcohol swaps.
Removal/reductionof pathogenic microbes inside the body;e.g.,antibiotics.
Mode of action: of Autoclave (physical)
Mode of action: Dry heat incineration (physical)
Mode of action: Ionizing radiation (physical)
Mode of action: Membrane filters (mechanical)
Mode of action: Ethylene oxide (chemical)
denatures DNA and inactivates proteins
Mode of action: Phenolics (chemical agent)
block bacterial fatty acid synthesis
Mode of action: Alcohols (chemical agent)
denature proteins and dissolve membrane lipids
Mode of action: Halogens (chemical agent)
oxidizing agent - denatures proteins
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