Week Three Microbiology Notes
Week Three Microbiology Notes MMG 301
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This 14 page Class Notes was uploaded by Marco Lin on Sunday September 20, 2015. The Class Notes belongs to MMG 301 at Michigan State University taught by s. mulrooney in Fall 2015. Since its upload, it has received 61 views. For similar materials see Introductory Microbiology in Journalism and Mass Communications at Michigan State University.
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Date Created: 09/20/15
Page 1 Note Taker Marco Lin Professor Dr Mulrooney MMG 301 Date 9915 to 91115 Key Bold is important Underline is class speci c assignments etc italicize is topics I do not own or take credit of most images links or works cited are found near images or end of notes MMG 301 Week Three Notes 91415 Prokaryotic Cells Inclusion Functions Inclusions inclusions are structures that may include membranes With membranes involve in energy production usually require membranes in order to generate a membrane differential protonenergized Examples thylakoid membranes of photosynthetic cyanobacteria and membrane enclosed anamoxosome Large Aggregated molecules storage polymers nucleoid mineral deposits Large molecular structures gas vesicles endospores Nucleoid a large aggregated structure of DNA and proteins DNA is formed in supercoils coil in a coil by enzymes known as topoisomerases to created an aggregated nucleoid and this fits 46 million pairs into 12 micrometers Proteins are responsible putting the twisted DNA form into domains Some antibiotics inhibit the formation of the nucleoid Nucleoids can be seen in TEM transmission electron microscopy Spirochetes or axio laments thin coiled bacteria with an internal agellum Page 2 Endoflagella internal agella that are located in the periplasm Spirochetes have endo agella Endoflagella are rigid and helical The rotation of the agella makes the cell corkscrew thus it can move through a suspending medium this allows the cell to drill through something like a mucus membrane Microbes ability to store energycarbon Storage polymers accumulate when there is excess energyfood Polymers degrade to furnish energy for sustain growth and is a good reserve for energy Examples polybetahydroxybutyrate PHB four carbon polymer and when large enough it is no longer soluble glycogen polyphosphate sulfur Glycogen common carbon storage polymer made of glucose Long branched polymer of alphalinked 14 glucose units with betalinked 16 branches Forms cytoplasmic granules when carbon source is in excess Glycogen is degraded when carbon is low Polyphosphate granules store phosphate and energy Linear polymer of highenergy inorganic phosphate esters Can be found in all domains of life Can substitute for ATP as a source of energy It can replace ATP to phosphorylate glucose for glycolysis Page 3 Prokaryotes that uses sulfur lipotropic organism inorganic metabolism Insoluble sulfur is deposited during lithographic metabolisms energy is made from oxidation of inorganic electron donors of H28 sulfuric acid by various sulfur bacteria Can provide the cell with energy by oxidizing sulfur to sulfate When sulfuric acid is exhausted granules disappear Gas vesicles provide buoyancy to photosynthetic aquatic prokaryotes Hollow enclosed spindle shaped structure consisting of 2 proteins GVpA and vaC Permeable to dissolved gases but not to water and solutes The Gas Vesicles help photosynthetic bacteria in the photic zone light zone of aquatic environments Positions aquatic chemoorganotrophic bacteria in the photic zone where dissolved organic matter is more abundant Hammer experiment what happens if vesicles are destroyed When the gas vesicles collapse the bacteria sink and they must make new gas vesicles to regain buoyancy Ena ospores very resistant Bacterial endospore is formed in a survival situation Dispersal mechanism is engaged by 20 genera of grampositive bacteria Sporulation The process of forming an endospore This is when a vegativtive growing or metabolizing cell is converted into a dormant metabolically inactive endospore endospores are like resistant seeds Germination When a spore contacts a good environment and convert to vegetative cell similar process when a seed becomes a plant Endospore and important pathogens Page 4 Most endospore are low Genetic Content DNA levels below 50 percent grampositive bacteria Bacillus rod shaped cells Examples of bacillus l B thuringiensis produced proteins that are toxic to insect larvae used for nonchemical pesticide in agriculture 2 b subtilis not harmful and is used in laundry detergent model bacterium for endospore formation 3 B anthracis causes anthrax Clostridium rods Includes bene cial species as well as signi cant human and animal pathogens Examples 1 C perfringens pathogen causes gangrene and food poisoning 2 C tetani causes tetanus 3 C Botulinum botulism Bacillus Subtillis model 1 Vegetative growth stops due to unfavorable conditions nutrient starvation 2 Asymmetric cell division of the cytoplasmic membrane 3 A prespore is engulfed by the cell membrane thus the endospore has two membranes 4 Cortex formation 5 Coat formation incorporation of calcium acidsoluble proteins and dipicolinic acid 6 Mature 7 Release Endospores contain essential DNA and enzymes Exosporium the outermost protein covering Spore Coats several layers of specific proteins Cortex peptidoglycan Core surround by core wall Page 5 Contains nucleoid DNA ribosomes cytoplasmic membrane and essentials for germination Endospore core contains large amounts of dipicolinic acids that forms large complexes with calcium Dipiclonic acidcalcium complex stabilizes DNA and binds water Spore acidsoluble proteins DNA protection 91615 StructureFunction of Bacteria 4 External Components Components external of the cell wall provide adhesion Pili Fimbrae Capsule and Slime later protection S layer Slime Layer and Capsule and motility agella and rarely pili Some prokaryotic Cells have capsules or slime layers Matrix of polysaccharides and or polypeptides outside the bacterial cell wall Capsule A semirigid matrix with a de ned border that contours the cell This excludes India ink black and this excluded from the capsule particles Slime Layer Nonrigid matrix that easily deformed This does not exclude India ink particles Slime layer consist of often polysaccharides glycocalyx rarely amino sugars or polypeptide bacillus anthracis Negative Staining India Ink staining everything that we do not want to see This let us see ne carbon particles Capsules and slime layers have multiple functions 1 Physical Protective barrier water retention to resists desiccation drying protection from immune system 2 Promote cell Aggregation occulation free oating suspended in liquid 3 Adhesion to surfaces Requires for biofilm formation and aids pathogenesis Page 6 F imbriae Fimbriae consist of protein assembled into a thin tube different from agella Fimbriae Adhesion Functions 1 host cells 2 inanimate surfaces 3 each other Fimbriae contains adhesins proteins that bind to specific saccharides and or proteins found on the surface of host cells Host Speci city and tissue Tropism specif1c recognition and binding to adhesins Example Uropathogenic E coli have f1mbriae that binds to the urinary tract Binding to hosts is the rst step for infection Fimbrae are thinner shorter and more numerous than agella Pili Pili protein filaments that binds to other cells and exchange genetic material Some pili can be used for motility Pili are longer and less numerous than f1mbriae Pili can elongate or retract with modifying proteins Conjugation take one DNA from one cell and transfer it from another cell Pilli attaches the two bacteria together Pilus is a hallow tube of protein so that DNA can move through Two important types of pili are Conjugative pili and type IV pili Some pili can function in adhesion ta host cell tissue Type IV pili can be extended and stick to a surface and can depolarize to retract and pull in the object This is called twitching motility Microbes in the News Arizona children hit hard in cucumber salmonella Read the first three paragraphs Where did the cucumber come from Page 7 How many states were involve What percentages of those who got sick have been hospitalized Assigned reading Serotype reading from the CDC Serotype information for the CDC read the serotypes and the importance of serotyping salmonella Link is on D21 F lagella Motility allows the ability to disperse and nd more favorable conditions Reasons for moving better environment 1 nutrient limitation 2 accumulation of wastes 3 escape from defenses and predators Flagella a helical protein appendage that rotate to provide propulsion through the suspending medium Some microorganism s agella can only rotate in one direction or stop Some microbe s agella can be reversible The location of Flagella can very Peritrichous all over Polar one end or the other Lophotricous several on one end Parts of the Flagellum 1 Basal body embedded in the cell membrane and acts as a motor 2 Hook a hallow curved protein that connects the basal body to the filament Page 8 3 Filament hallow long protein helical structure and there is a periodic and characteristics wavelength and amplitude The rotation of the agella is powered by a protein motor that is embedded in the cytoplasmic membrane The agella motor is in the basal body and composed of a rotor and a stator The stator stationary consist of mot proteins that drive rotation of the rotor The rotor consists of a central rod surrounded by the C MS P and L rings The Mot proteins provide torque by using proton motive force Flagella of some microbes can rotate on both directions while some cannot Flagella can rotate up to 18000 rpm The agella are formed in a step wise process 1 Proteins of the MS and C rings are developed rst 2 Proteins for the subsequent parts are exported through the hallow core 3 Mot Proteins p and L rings 4 The hook proteins are followed by the lament proteins and lament is principally made of a protein called agellum Bidirectional Flagellum Most prokaryotes with paritrichous agella can reverse direction of rotation When the cell is moving forward run agella form into a bundle that move in unison When agella reverse rotation try to move outward from the cell and pushed apart tumble The tumble serves to redirect the cell Polar agellum with reversible rotations moves similarly Page 9 Polar Flagellum with unidirectional rotation reorients during a brief stop in rotation followed by resumption of rotation Many prokaryotes can sense their chemical environment and respond by moving towards or away from the chemical Example if there is no chemical the movement is completely random If chemical is present the run becomes longer and tumbles becomes less frequent Net result is movement towards the higher chemical concentration Chemotaxis the sensing of chemicals and the associated changes in movements Chemotaxis can be demonstrated using a capillary tube assay 1 Insertion of a capillary tube containing a control 2 The control contains salt 3 The accumulation of bacteria in capillary containing an attractant 4 Repulsion of bacteria by a repellent 5 Time course showing cell numbers in capillaries containing various chemicals Types of Taxis Phototaxis Movement towards light or specific wavelengths Aerotaxis Movement towards or away oxygen Osmotaxis Movement towards or away high ionic strength concentration Magnetotaxis Movement to orient within the earth magnetic field 9 18 15 MMG Metabolism l bioenergetics and fermentations Metabolism the sum of anabolism and catabolism Catabolism Biochemical reactions that are degradative carbon consuming energy generating Page 10 Anabolism Biochemical reactions that are building in function require an expenditure of energy and are also referred to as biosynthetic reason Growth of microorganism requires chemicals carbon hydrogen oxygen nitrogen sulfur and other in smaller amounts Energy provided by biochemical reactions or light Autotrophs Inorganic C02 carbon source organisms Heterotroph Organic carbon source Chemolithotroph Inorganic chemical energy source Chemoorganotroph organic chemical energy source Phototroph Light Energy Source Energy Yields of a reaction Gibb s free energy can be calculated from free energy formation of the reactants and products Energyyielding reactions exergonic gibbs is negative Energyrequiring reactions endergonic gibbs is positive Oxidationreduction redox Reactions that involve the movement of electrons from a donor to an accepter molecule The electron changes its energy state This reaction is accompanied by changes in energy for that electron Many chemical reactions in biological systems involve the movement of electrons from one energy state to another For exergonic energy yielding reaction the electron from a higher energy state to a lower one The loss of an electron from an atom or compound is an oxidation The gain of an electron is reduction Page 11 Note OILRIG Oxidation lose electrons Reduction gains electrons Note Leo the Lion Gers lose electron is oxidation gain electrons is reduction Redox Tower For a redox reaction if electrons move down the redox tower the reaction will yield energy Examples of reactions with H2 as e39 donor 1 H2 fumurute239 gt smtinale2 Redox couple COzlglucose 043 24 equot 2HIH2 042 2 e39 COZImethanol 038 6 e NADINADH 032 2 e COzlacetate 028 8 equot 1 AG 39 00 kJ 39 2 H2 N03 gt N02 H20 s st 028 2 e 5037st 022 s e PyruvateIactate 01 9 2 equot 54062752032 0024 2 e39 quot Fumaratesuccinate 003 2 e Cytochrome boxm 0035 1 e 2 AG 453 kJ 3 H o H20 A60 237 kJ Figure 59 Brock Biology of Microorganisms 11e 2006 Pearson Prentice Hall Inc Fe3lle2 02 1 e39 pH 7 Ubiquinoneomed 011 2equot Cytochrome coxm 025 1 e Cytochrome aoxlmd 039 1 e gt NO339IN0239 042 2 equot N03quotN2 074 5 e 393 Fe3Fe2 076 1 239 pH 2 39 golezo 082 2 e I I I Page 12 A variety of electron carriers are used they carry 1 or 2 electrons at a time These include NAD avins FMN or FAD and quinones Cofactors transfer electrons by interacting with proteins or enzymes Carrier of 2e and 2H NAD or DADP transfers electron and protons by accepting these from a reduced enxyme and then donated electrons to an oxidized enzyme The enzyme accepting the electrons uses them to reduced a substrate and generate a product OxidationReduction Reactions Carriers of electrons only Review of Redox Oxidation loss of an electron Reduction gain of an electron Electrons cannot be free in solution so oxidation are coupled with redox ractions redox couples In some biological reaction a proton and electron are transferred togerh in other reactions only electrons are transferred Redox Potential a measure of the tendency to given up an electron Energy is stored in compounds containing high energy bonds High energy bonds are created from energygenerating pathways The bonds are broken to yield energy for anabolic reactions Water is removed when anhydride bonds are created Water is split hydrolysis when anhydride bonds are broken There are two basic strategies om makingAT P l Substratelevel phosphorylation Page 13 ATP is generated from energy rich intermediates Fermentation pathways make ATP by substratelevel phosphorylation Glycolysis is fermentation of glucose and is found in nearly all organism 2 Oxidative phosphorylation Cytoplasmic membrane becomes energized creating a proto motive force A proton gradient is created across the membrane Phosphorylation of ADP to ATP is coupled to the generation of the proton motive force by respiration In phototrophs light drives photophosphorylation Glycolysis anaerobic Does not consume oxygen Universal Low energy yield compared to respiration Splits glucose 6C to two pyruvate 3C and then to nal products based on organism Produces a net of 2ATP per glucose and 2 NADH consumed to produce nal products NADH is generated from glycerldehyde3phoshpate is later oxidized for production of fermentation end products Lactic acid fermentation in lactic acid bacteria the end product is lactic acid for homofermentative pathways Heterofermantative pathways is lactic acid ethanol and c02 Stickland fermentation uses amino acids as a substrate Amino acids to organic acids ammonia c02 depending on amino acids used Page 14 Genus clostridium pathogen this pathogen that forms spores and it turns animals to a goo so they can feed They export protease enzyme and it takes proteins of the host and convert that to amino acids that is fermented
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