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MICROBIOLOGY
Introduction & Classification
Topics
• Classification
• Methods of Microbiology
• Nutrition & Growth
• Microbial Structure
• Metabolism
• Host parasite relationships
• Control of Growth
Types of Microorganisms
• Bacteria– Gram positive & gram negative
• Viruses– RNA & DNA
• Fungi– Yeasts & molds
• Protozoa
History
• Robert Hooke– Described units in cork as cells
Anton van Leeuwenhoek-1667– Made lenses or simple microscopes
Spontaneous Generation
• Abiogenesis-living matter arising from nonliving matter
• Redi –maggots & meat
• Pasteur et al disproved abiogenesis
Pasteur
• Fermentation– Yeast ferment grape juice –alcohol– Bacteria ferment grape juice-acids
• Pasteurization
Germ Theory of Disease
• Koch– Koch’s postulates
– Developed pure culture techniques
– Discovered TB agent
Immunology/Chemotherapy
• Jenner and smallpox vaccine– Used cowpox virus
Antiseptics
• Semmelweis
• Lister
Fleming
• Discovered penicillin
Taxonomy
• System of cataloging organisms– Identification: characterization of organisms
– Classification: arrangement of organisms into similar groups
– Nomenclature: assign names
Binominal Nomenclature
• Genus-capitalized ; collection of species
• Microbes – species can be subdivided into strains
• Strains have small genetic differences
Rules
• Both genus & species underlined or italicized
• Strain-subdivision of species– ID by name, number or letter– Example- Escherichia coli- E. coli K12
Classification
• Wittaker-5 kingdoms– Plants– Animals– Fungi– Protista– Monera or Prokaryote
Domains
• Carl Woese-1980s
• Based upon modern techniques– Sequence of rRNA in ribosomes
• Three cell types based upon ribosomes
Three Domains
• Domains above kingdom level
• Bacteria or Eubacteriae– Prokaryotes with peptidoglycan in cell wall– Divide by binary fission– Motile by flagella or cilia– Sensitive to antibiotics
Archaea
• Ancient prokaryotes– Cell wall present, not peptidoglycan
– Live in extreme environments
– Have unusual metabolic processes
– Not sensitive to antibiotics
Archaea
• Methanogens -strict anaerobes– Produce methane from CO2 + H2
– Live in anaerobic mud lakes
– Intestine of cows
Archaea
• Halophiles– Require high concentration of salt
• Maintain cell wall
– Spoilage of food-salted fish
– Salt lakes
Archaea
• Thermophiles– Live in hot sulfurous waters or acidic water
– Nucleic acids/proteins do not function at low temperatures
– Volcanic vents in ocean
Eukarya
• All eukaryotes
• Cell wall varies in composition
• Not sensitive to antibiotics
• Fungi-yeasts and molds
• Protists-slime molds, protozoa, & algae
• Plants & animals
Endosymbiotic Theory
• Eukaryotes evolved from prokaryotes
• Supported by similarities between prokaryotes & organelles in eukaryotes
• Mitochondria & chloroplasts same size as prokaryote cell– Contain DNA, 70S ribosomes
• Endosymbiont-organism that lives within another
Support for Theory
» Prokary Eukary Mitoch & Chloro
• DNA circular linear circular
• Histones No Yes No
• Ribosomes 70S 80S 70S
• Growth binary mitosis binary
• Cyanophora
Viruses
• Obligate intracellular parasites
• Not cells so non living agent
• No ribosomes
• Classification is different
Viroids & Prions
• Viroids– Single short piece of RNA– Cause disease in plants – ? In humans
• Prions– Protein– Cause neurodegenerate diseases– Humans & animals– CJD & mad cow
New Challenges
• Antibiotic resistance– MRSA, VRE & ESBL
• Emerging diseases– SARS & Avian Influenza
• Bioterrorism– Anthrax, smallpox, plague, botulism