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Microbiology and Immunology
Microbiology and Immunology 4200B
Susan Koval

Ch 2 Notes March0614655 PM25 Elements of Microbial StructureAll cells have permeability barrier separating cytoplasm from outer environmentAlgae and protozoa are eukaryotic because theyre protistsProkaryotes dont have organelles simple internal structure they can also couple transcription and translation in same area because their DNA isnt bound into nucleusViruses are major classes of microorganisms but theyre not cellsMuch smaller and lack many characteristics of cellsVirus particle is static and stable not dynamicOnly able to replicate once inside another living organismViruses dont have ribosomes27 Evolutionary Tree Of LifeEvolution is process of descent generating new varieties via modification of some sorts creating new speciesOccurs in any selfreplicating systemCaused by mutation and determined by survival In this time both cells and viruses can evolveCan determine phylogenetic relationships by comparing genetic info in nucleic acids and in proteins particularly ribosomal RNAs because theyre found in all cellsViruses lack ribosomes so have to use different molecules to determine relationshipsThe three phylogenetically distinct lineages aka domainsare Bacteria Archaea and Eukarya which are the main branches of phylogenetic treeTree tells us two important things about evolutionNot all prokaryotes are closely related1Archaea are more closely related to Eukarya than Bacteria2Thought that multicellular organisms arose from eukaryotic microorganisms which branch off from the tree early on in lineageMolecular sequencing and other methods shown that eukaryotic cells have genes from cells coming from two different domainsAs well chloroplasts and mitochondria have their own genomes circular DNA and ribosomesThought that these organelles came from Bacteria which came into cells and associated with them close enough to form endosymbiosis29 BacteriaAll known pathogenic prokaryotes are Bacteria Viruses arent alive so arent consideredLargest phylum is ProteobacteriaMany chemoorganotrophs in this phylum ie E coliMany common prokaryotes found in soil and water and those that live in animals and plants nonpathogenically are in this phylumMitochondria thought to have evolved from this phylum Microbiology TUTORIAL and Readings Page 1 Mitochondria thought to have evolved from this phylumMany types of pathogenic bacteria are gram positive as well no cell wall small mycoplasmasgenomes also GMycoplasma is very important genus in pathogenic bacteriaSome Archaean cells ie Thermoplasma Ferroplasma lack cell walls tooCyanobacteria are related to G phylogenetically and are oxygenic phototrophsChloroplasts related to themFirst oxy photos to evolve on Earth so theyre very important in evolutionCyanobacteria produced Oas a byproduct and after doing so for a very long time there was 2enough oxygen in Earths atmosphere for cells to start respiration with itOther phyla have distinct morphologies and theyre GTwo major phyla are phototrophic green non sulfur bacteria which are also autotrophsMicrobial Mats laminated microbial communities containing phototrophs and chemotrophsie Chloroflexus is filamentous phototroph found in this configuration in hot springs important because their ancestors may have bee first phototrophic bacteria on Earth andare also major phylaChlamydiaeDeinococcusThermushas many human respiratory and sexually transmitted pathogens intracellular Chlamydiaeparasites which lets them avoid immune response for a whilehave species with weird cell walls and naturally resistant to high levels of DeinococcusThermusradiation major species is because it can survive radiation thats much more potent radioduransthan the level that can kill humans also when its faced intense radiation and breaks up can reassemble its chromosomeThought that early life forms were hyperthermophiles210 ArchaeaTwo phyla and EuryarchaeotaCrenarchaeotaBoth form major branch on treeMost cultured species are extremophilesAll are chemotrophic some can use light to make ATP ie Halobacterium but differently from phototrophic organismsSome use organic compounds while others are chemolithotrophs mainly using Hgas2Chemolithotrophs mainly in hyperthermophilic Euryarchaeota has four groups Methanogens1Strict anaerobesUnique because energy stored as methaneExtreme Halophiles2Related to methanogens but physiologically differentMost need oxygen and need large NaCl for metabolism and reproduction therefore live in very salty environmentsMicrobiology TUTORIAL and Readings Page 2 in very salty environments Thermoacidophiles3Grow best in high temps and very acidic pH ie Thermoplasma which lacks cell wall and Picrophilus most acidophilic prokaryote knownHyperthermophiles Some4oOptimally grow in temps above 80CMany different configurations like methanogenesis reducing sulfursulfate and iron oxidationMost are autotrophs because gets their carbon from CO2Aerobic or anaerobicMost cultured Crenarchaeota are hyperthermophilesEither chemolithotrophs or chemoorganotrophsMost are anaerobes because high temperatures anoxic environmentsMany use Hin environment as energy source2Some live in places that arent thermal environmentsie many live in open oceans where its cold and very oxicMany of these marine types are chemolithotrophs that use NHas energy source dont know 3much about their metabolism yetCrenarchaeota found all throughout in nature detected in soil and freshwaters as well Microbiology TUTORIAL and Readings Page 3
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