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BI276 exam review notes.docx

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Wilfrid Laurier University
Hany Anany

Nutrition and CultureMicrobial taxesoTaxis directed movement in response to chemical or physical gradientChemotaxis response to chemicalsPhototaxis response to lightAerotaxis rspobse to oxygenOsmotaxis response to ionic strengthHydortaxis response to waterMetabolism The sum total of all chemical reactions in the cellCatabolic reactions catabolismoEnergyreleasing metabolic reactionsAnabolic reactions anabolismoenergyrequiring metabolic reactionsNutrientsoSupply of monomers or precursoes required by the cells for growth to form macromolecules Protein DNA lipidsoDifferent organisms need different nutrientsoC H O and N constitue the bulk of the cellwater makes up 7080of the cell weight protein 55 of the cell dry weightMacronutrients those required in large amountso1 CarbonRequired by all cellsMajor element in all classes of macromolecules50 cell dry weightHeterotrophs use organic carbon autotorphs use inorganico2 Nitrogen13 dry weightKey element in proteins NAs and many more cell constituentsoOther MacronutirentsPhosphorusNAs and phospholipidsSpplied as phosphateSulfurAAsVitamins and coenzyme ASupplied as sulfide and sulfatePotassiumRequired by enzymes for activityMagnesiumStabilizes ribosomes membranes and NAsRequired for many enzymesCalciumStabilize cell wallsKey role in heat stability of endospores interacts with diplochloronic acidSodiumRequirement is based on habitatMicronutrients those required in trace amountso1 IronKey component of cytochromes and FeS porteins involved in theelectron transport system aerobic respirationUnder anoxic conditions general ferrous Fe2 solubleUnder oxic generally ferric Fe3 form insolubleCells produce siderophores ironbinding agents to obtain iron from insoluble material form an transport them to the cellso2 Growth FactorsOrganic compounds required n small amount by certain organismsVitaminsoMost commonly required growth factorsoMsot function as coenzymesAAs purines pyrimidinesCulture mediaoNutrient solutions used to grow microbesTwo broad classesDefined media precise chemical composition is knownComplex media composed of digesets of chemically undefinted substances eg yeast and meat extractsoEnrichment mediaUsed to culture difficult to grow or low number microbes contain special nutrientsoSelectiveSelectively inhibits growth of some and promotion of othersoDiffernetialAn indicator that detect particular chemical reactions occurring during growthoImportant to know the protper nutrient requirements for successful cultivationLanboratory cultureoPure culture containing only a single kind of microbeoContaminants unwanted organiss in a cultureoCells can be grown in liquid or solidSolid are prepared by addition of a gelling agent agar or gelatinCells form isolated masses colonies on the medioPure culture techniqueStreak platPour plateSpread plateMicrobial GrowthBacteiral Cell divisionoCell growth and binary fissionGrowht increase theof cellsBinary fission cell division following enlargement of a cell to twice its minimum sizeGeneration time time required for microbial cells to double in nmberEach daughter cell receives a chromosome and sufficient copies of all other cell constituents to exist as an independent celloStepsCell elongationSpetum formationCompletition of septum formation of walls cell separationoFts Proteins and Cell divisionFts filamentous temperaturesensitiveEssential for cell division in ALL prokaryotesInteract to form divisome cell division apparatusoFstZ forms ring around centre of cell will eventually become the cell division plate related to tubulin important cell division protein in euksoZipA anchor connects FtsZ rings to CM and stabilizesoFtsA connects FtsZ ring to membrane and recruits other divisome proteinsrelated to actinthe divisome forms well after elongation of a newborn cell has already begun of the way into cell divisionBefore divisome forms th cell is already elongatin and DNA is replicatedLocation of the FtsZ ring is facilitated by Min proteinsoMinc C and D inhibit cell division by preventing FtsZ ring formationoCentre of the cell has the lowest Min C and Min D concentrationsmaking centre most permissice site for FtsZ ring assemblyoMinE proteins ensure that the divisome forms only at the cell centre and not poresoMreB and Determinants of Cell MorphologyProks contain a cell cytoskeleton that is dynamic and multifacetedMreB major shape determining factor in prokaryotesForms simple cytoskeletonForms spiralshaped bands around the inside of the cell under the CMNot found in coccusshpaed bacteriatherefore coccus is default shape and rods have this geneAssits in segregation of the replicated chromosome FtsK also helps thisLocalizes synthesis of new peptidoglycan and other cell wall components to specific locations along the cylinger of a rodshaped cell during growth
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