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BIOL 240
Trevor Charles

Module 1introduction to MicrobiologyMicroorganisms have an impact on almost all of the biology on earth and influence how earth has developed making up over 50 of the biomass on earthRead through chapter on macromoleculesWhat is Microbiology The science of microorganisms very small unicellular organismsOver a century old discipline The American Society of Microbiology is the largest life science organization in the world Given rise to molecular biology and biotechnology What are Microbes Prokaryotic Archaea BacteriaEukaryotic Algae Fungi Protozoa Bacteria interact with different organisms symbiotic relationshipo ie Rhizobium bacteria fill in the root nodule of a plant to convert N to 22NH provides nutrients through nitrogen fixation3What makes a cell alive Metabolism takes in chemicals turning it to energy Cell growth Cell differentiationCell communication excretion of chemical signals Cell mobility Cell evolution mutations resulting in new speciesHow did life originate Evolution resulted in the universal ancestor approximately 4 billion years ago Organisms are biochemical machines that convert chemical into energy and macromolecules and divide biochemical view Organisms are genetic machines containing DNA to carry out cellular function genetic view The Historical Roots of MicrobiologyBegan in the last century Most common causes of death were infectious diseases influenza tuberculosis gastroenteritis in the 1900s not as much now o Better sanitation and antibiotics resulted in the huge reductions of mortalityTowards the end of the 1800s people knew that microorganisms existed and could be seen under the microscopeTheory of spontaneous generation of microorganisms was debated by researchers airborne food spoiling Louis Pasteurs 1850 experiment involved a nonsterile liquid was heated and cooled repeatedly and left to observe for microorganisms dust and other microorganisms were prevented from coming in contact with solutiono Spontaneous generation did not occur and was not observed o Pasteur allowed contact with dust and resulted in growth of microorganismso Theory of spontaneous growth disproved by experimentKoch Postulates was a series of postulates formed to prove that microorganisms can cause diseases by Robert Koch germ theory of diseaseo Experiments were done with Bacillus Anthracis showed that the blood of diseased rats contained bacterial cells as well as red blood cells o Observation alone cannot prove that the bacterial cell is cause of death of the rat and the blood of healthy rats does not contain bacterial cellso Postulate 1 the suspected pathogenic organism should be present in all cases of the disease and absent from healthy animalso Postulate 2 The suspected organism should be isolated and grown in pure cultureo Postulate 3 The cells from a pure culture of the suspected organism should cause disease in a healthy animal obtained from Postulate 2 o Postulate 4 The organism should be reisolated and shown to have the same pathogen as the originalo Concluded that specific organisms cause specific diseaseIntroduction to Cell Structure and the Three Domains Prokaryotic cells bacteria and archaeal cells do not have a nucleus and the DNA is not surrounded by a nuclear membraneEukaryotic cells have the DNA within the nuclear membrane also contain mitochondria and chloroplasts in plantso Arose from an archaeal type of organism that engulfed other cells Sequencing of the small ribosomal RNA gene 16S rRNA in bacteria and 18S rRNA in eukaryotes has lead to new knowledge of relationships between different forms of lifeo Closely related organisms will possess similar sequenceso Isolate DNA of interest PCR to amplify gene sequence gene comparison of sequences phylogenetic tree 3 domains in the tree of life bacteria archaea and eukarya Module 2 The Physiological Diversity of MicroorganismsIn order for a microbial cell to grow it has to be able to take in energy and carbon compounds from the environment o Preferred habitat is determined by its physiology adaptationThe two main sources of energy for microorganisms are chemicals chemotrophy and light phototrophyChemoorganotrophs organic chemicals such as glucose acetate etco Heterotrophs get their carbon from preexisting organic compounds o ie humans 2 Chemolithotrophs inorganic chemicals such as H HS Fe NH etc224o Only prokaryotes no eukaryoteso Oxidation of inorganic chemicals provides energy for carbon fixation Phototrophso Most are photoautotrophic and get their carbon from CO fixation2o Autotrophs receive their energy from inorganic sourceso ie plants The Domain Bacteria Proteobacteriagramnegative bacteria eg E coli Grampositive bacteriaCyanobacteriaThe Domain ArchaeaMost exist in extreme environments also swamps and rumen of cows Envmarine organisms found to exist in marine environments nonextreme environment O Limit for growth at high temperatures is over 113C ie Pyrococcus Methanogens exist in environments with high methane concentrationsSome organisms may grow at a pH less than 0The Domain Eukarya The diversity of eukaryal organisms in dominated by microbial species o Early branching eukaryotes lack mitochondria Endosymbiotic Theoryan archaeal organism evolved a nuclear memebrane before or after engulfing a bacterial organism and developed a symbiosis relationship which evolved into an obligate relationship neither can exist without the othero The bacterial organism in the relationship evolved to become the mitochondria of the eukaryotic organismo An engulfed cyanobacterial organism could have evolved to become the chloroplast in a planto Recent work shows considerable sharing of genetic material between the symbionts
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