Week 3 Lecture Notes: Microbiology 101
Week 3 Lecture Notes: Microbiology 101 101.0
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This 10 page Class Notes was uploaded by Isabel Markowski on Friday September 25, 2015. The Class Notes belongs to 101.0 at University of Wisconsin - Madison taught by a professor in Fall 2015. Since its upload, it has received 41 views. For similar materials see General Microbiology in Microbiology at University of Wisconsin - Madison.
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Date Created: 09/25/15
Microbiology Week 3 Lecture Notes Microbial Growth 0 For microbes generally an increase in numbers 0 Growth population growth not an individual cell too tiny 0 Includes developmental processes 0 Common Mechanism Binary Fission 0 Cell gets bigger and divides in half at septum division lineplane 0 Generation time doubling time time for one division to occur 0 080 minutes 0 Each daughter cell needs full genome must divide replication of DNA cytoplasmic contents etc 0 Major proteins o Asexual Min System FtsZ Ring 0 Set Of many proteins oOnce middle is known 0 Min C and Min D FtsZ forms ring around 0 Prefer to aggregate at ends cell and squeezes like a of cell belt to form septum 0 Min E oCycoskeeta protein 0 Will push CD Off 0 Dynamic 0 CD will go to other end 0 E returns and process is repeated to set up parameters n Indirafnc Alth D rmll c mirlrilo 0 Consequences Daughter cells clones 100 of population is capable to reproduce rapid growth Clonal and exponential growth 2quotn where n generation 2 offspring per generation gt one gt cell two cells four cells What do microbes need for growth Energy source 0 Energy ability to do work cellular functions making more cells movement transport 0 Chemotrophs organismsuse chemical energy 0 Phototrophs use light energy Macronutrients and Essential Elements 0 Nutrients assimilated take elementnutrient directly make into biomass 0 Ex C O N 0 Carbon assimilation into ceuar molecules CH20n Other CH4 7 CH20n gt Central Carbolnl Metabolism containing molecules CO2 Autotrophs use C02 as carbon source 0 Produce organic material primary producers 0 C02 is quotfixedquot It39s reduced and a CC bond formed making organic carbon Reducing power is needed electrons Energy is needed ATP At least 6 different pathways for CO2 fixation 0 Most common CalvinBensonBassham Cvcle Start with 3 C02 Added to RuP make CC bonds Processed redox reaction and reduced Cyce Start with 15 C add 3 18 C atoms get rid of 3 0 Many microbial autotrophs O Heterotrophs use organic material as carbon source 0 Consumers 0 Common protists fungi bacteria and archaea o Any diseasecausing microbe PhotoautOtI ODhS Chemolithotronhs Cyanobacteria Algae Nitri ers Sulfur oxidizers Hydrogen oxidizers o 100039s of possible organic chemicals can be used microbes DIVERSE Secreted enzymes 0 0ften needed to degrade organic polymers before transport 0 Microbes needdigest polymers into monomers externally before transport into cell 0 Proteases nucleases lipases gycosidases amylases ceuases 0 Practical applications detergents Methanotrophs use Methane as carbon source Only some bacteria can do this Abundant in environment 0 Use methane as energy source and make more cells 0 0 Nitrogen 0 Most use either Ammonia NH3 Nitrate NO339 Organic Nitrogen aminoacids nucleotides 0 Diazotrophs quotfixquot Nitrogengas N2 gt 2 gt NH3 gt Amino Acids other N containing molecules Reduction of Ngas to ammonia N limiting for growth limited amount Nitrogen Fixation Pathway widespread in Bacteria and Archaea no Eukaryotes Enzymes very oxygensensitive BacteriaArchaea must protect enzymes Requires energy ATP and reducing power electrons o N O C02 few small moleculesdiffuse across cell membrane don39t need transport system Nitrogefixing microbes heljp animalsplants Ex termites Ndeficient diet so bacteria help Legume plants Ndeficient soils 0 Other nutrients o Micronutrients needed in small amounts K potassium Ca Mg Na 0 Trace Elements needed very small amounts B Cr Co Cu Fe Mn Mo Ni Se W V Zn 0 Growth Factors organic compounds required by certain organisms Cells have requirement but not synthetic capacity Vitamins amino acids purines and pyrimidines fatty acids and lipids OO O Nutritional SelfSufficiencv Varies Nutritionally Independent 0 Obtain simple chemicals from environment 0 Use thesemake all it needs 0 Phototrophs Nutritionally Dependent fastidious o Often lack anaboliccatabolic pathways 0 Need nutrients and growth factors supplied to them Appropriate Environmental Conditions 0 Temperature pH water activity oxygen level 0 Many anaerobic habitats exist soilssediments termite gut Temperature Psychrophile Mesophile Thermophile hyperthermophile Cold 4 C Limits of cell s growth temp range Hot 88 C pH external Acidophiles acidic Alkaliphiles alkaline 0 Low temp s membranes gelprotein function too slow 0 High temp s membranes dissolveproteins denature W Determines Growth Obligate Aerobe absolutely requires 02 Microaerophile Requires 02 but not full conditions Facultative Aerobe Grow better in 02 but also in nonOz environments Most VERSATILE Aerotolerant without regard to 02 Everywhere Obligate Anaerobe Absolutely DOESN T require 02 OZ has risks reactive oxygen species ROS o 02 reactive element 0 Superoxide hydrogen peroxide hydroxyl radical o Damage DNA proteins lipids Dealing with oxygen ROS 1 Cartoenoids protect absorb ROS 2 Enzymes detoxify ROS superoxide dismutase SOD catalase Catalase converts H202 to H20 and 02 Aerobes SOD and catalase Anaerobes lack these enzymes Catalase test add cells to H202 bubbles if produces catalases Solute Concentration Affects growth Dilute environment typical High solute environment 0 salt sugar other osmolytes o limits growth for many required for others Are Microbes alanSJrowing Survival Responses 0 No because energy sourcenutrients are limited 0 Environmental parameters aren39t favorable What happens 0 Cell response to limitations sense and acclimate Microbial Survival Response s Cvst Cysts Differentiated cells with increased environmental survival decreases metabolic activity 0 Turn off metabolismdivision when bad conditions 0 Turn back on with good conditions Giardia can form vegetative cells trophozoites and cysts o Trophozoites actively grow in intestinal tract and morph into cystform between hosts Microbial Survival Responses Endospores Special cell typeresponse to starvation Most resilient microbe Produce endospore leave unhealthy mother cell 0 Only few can 39 form endospores Bacillus and Clostridium endosporeforming Firmicutes Bacillus Clostridium Aerobic Anaerobic Manydon t cause 0 Manydon t cause disease disease Pathogens include B o Pathogens include C Anthracis and B Cereus tetani C botulinum and Endospore formation complex developmental process 0 Cell can either continue vegetative growth or endospore Very hardy multiple layers of protection 0 Resistant to heat harsh chemicals radiation dessication Can survive for many cells How do we study growth in lab Culturebased methodsisolatestudy Culturing growing microbe in lab Pure Cultures only one type of organism important Aseptic technique important Medium chemical formula usedgrow microbes Must know nutritional and environmental requirements Culturing from nature always selective not all grow in labs 100039s of culture media exist recipesoptimize growth conditions 0 De ned culture medium speci c 0 Complex culture medium just throw in a bunch of nutrients Critical to have appropriate medium matchmaking with microbe Social Lives Planktonic growth common 0 Cells grow as individuals suspended in liquid Microbial communities on surfaces bio lms 0 Ex tooth leaf surface Attachment Colonization Development Adhesion to solid surface Form polysaccharide complexforms buildingstructure lntercellular Communication growth and polysaccharide formation More growth and polysaccha ride Cellular Metabolism Energy Metabolism All cells need energygrowth Energy source chemotroph vs photototroph Energy from high potential energy electrons involved in redox reactions 0 Converted to ATP andor Proton Motive Force PMF for storage 0 ATP and PMF fuel cellular activities Energv Sourdf Electrgn Donor Biosynthesi Transport 5 transport movement etc etc HIGH Electron Donor oxidized Potential energy of electrons Carefully Controlled Redox Reactions i electron carriers ATPPMF Electron Acceptor reduced LOW Electron Donors and Acceptors Donors Chemicals w strong tendencygive up electrons become oxidized o Organotroph organic donor sugars amino acids lipids o Lithotroph inorganic donor ammonia hydrogen sul de Hgas reduced metals Acceptors Chemicals w strong tendencyaccept electrons become reduced 0 Oxygen nitrate su ate oxidized metals C02 some organic compounds Storing Energv from Redox Reactions Membrane storage electro chemical gradient PMF o Gradient form of stored energy 0 Chemical and electrical gradient AKA ion gradient Cytoplasm storage ATP amp other chemicals 0 Energy from catabolism energy for cell work ATP H ADP P 0 Cell energy stores interconvertible Energy gt Source Membrane Electrochem Gradient ATP ReverSIble rotary motor Synthase39 Uses ATP to make PMF or Energy gt Source ATP In cytoplasm PMF to make ATP How Do Cells quotcapturequot Energy from Redox Reactions 0 Either use 1 Electron Transport System respiration or phototrophy energy source to PMF 2 Substrate Level Phosphorylation respiration or fermentation energy source to ATP Chemotronhs l Chemooroanotroohv Chemolithotroohv l Organic Compound Fermentation Carbon Flow Chemoorganotrophs Ex E Coli 0 Use organic chemicals for energy 0 Can grow by respiration Using electron transport systemPMF Aerobic electron acceptor oxygen or Anaerobic electron acceptor doesn39t oxygen 0 Can grow by fermentation Substrate level phosphorylationATP 0 Some organic chemical used for carbon source as well 0 Glucose respiration in E Coli Donor Glucose Donor Glucose Oxidized to pyruvate electrons transferred to NAP39 Pyruvate further oxidized to C02 NADH transfers electrons to electron transport chain Electrons travel through ETC generaes PMF make ATP Electrons to acceptor Oxidation step supplies energy oxidation when have NADH 2 Pyruvate 2 net ATP 2 NADH The Redox Step 0 Energy from oxidation drives phosphorylation Electron transferred to NAD common electron carrier 0 NAD reduced to NADH gt oxidized The ATP Synthesis Step Substrate level phosphorylation Phosphate of substrate binds to ADP individually Further Oxidation of Pvruvate TCA CvcleKrebbs CvcleCitric Acid Cvcle Goal oxidate pyruvate produce C02 take electrons o Pyruvate oxidized to 3 C02 0 Electrons transferred to NAD or FAD electron carriers 0 Electron Transport Chain 0 Couples electron mvmt To generation of protein gradient 0 ln cell membrane 0 More electron carriers FeS Proteins Cytochromes heme Proteins Flavoproteins FAD FMN Quinones Q A small moleculemembrane 0 Lose a little energy with each stepgenerate PMF Mechanisms for generating ion gradient 0 Transfer of electrons bn different typescarriers through quinone Proton Pumps as accept electrons pump protons across membrane Final Step reduction of electron acceptor o Aerobic Respiration use 02 as acceptor o Anaerobic nitrate Reduction Use nitrate NO339 as acceptor Summary of Respiration Pyruvate is NOT a nal product of E Coli glucose respiration Output O 6 C02 0 Electrons on electron carriers 0 What happens when no electron acceptor o Fermentation Uses pyruvate as electron acceptor No need for ETCuses cytoplasmic reactions Substrate level phosphorylation Must recycle NADHNAD because only ATP made is that made by SLP during glycolysis Summary of EColi Metabolism Can grow by aerobic or anaerobic respiration 0 Organic molecules donor 0 Electrons travelETC to make PMF ATP made by ATP Synthase o Requires quotexternalquot electron acceptor Can grow by fermentation Many chemotrophs versatile both options like E Coli 0 Some only respiration 0 Some only fermentation Chemolithotrophs Inorganic electron donors as energy source Most also autotrophs ATP made by respiration same fundamental process as chemoorganotrophs Common types H oxidizers Sulfur oxidizers lron ox Ammonia ox Ex Ralstonia Eutropha o H gas electron donor 0 02 electron acceptor 0 C02 xed for carbon source
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