Microbiology Mid-term 1

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)

Plasma membrane extended inwards(endocytosis) and surrounded the nuclear region.

Mitochondria and Chloroplasts of eukaryotes originated from ingested prokaryotes.

• 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

• 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.

Interbreeding population of organisms that are repoductively separated from other groups.

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.

Protein Denaturation

cell denaturation

DNA damage

physical seperation

denatures DNA and inactivates proteins

block bacterial fatty acid synthesis

denature proteins and dissolve membrane lipids

oxidizing agent - denatures proteins