Week 2 Lecture Notes: Microbiology 101
Week 2 Lecture Notes: Microbiology 101 101.0
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This 9 page Class Notes was uploaded by Isabel Markowski on Saturday September 19, 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 84 views. For similar materials see General Microbiology in Microbiology at University of Wisconsin - Madison.
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Date Created: 09/19/15
Microbiology 101 Week 2 Notes Viruses 0 quotUltimate Parasitequot o obligate intracellular parasites must enter living host to replicate Microscopic infectious particles nonliving Don39t make own ATP sugars nada Extremely small 0 Bacterial E Coli 2 pm 0 Vs Virus 1 pm Virus Structure and Terms 0Naked Virus 0Envelope Virus 0 Nucleic acid 0 Nucleic acid 0 Genome is in protein 0 Genome is in membrane shell capsid made of envelope phospholipid capsomers bilayer o Bacteriophagebacteria 0 Common virus can still have n uenza herpes complex form etc 0Virus Genome Diversity DNA and RNA viruses 0 Not limited to doublestranded DNA 0Require living cell for replication 0 Lysis DESTRUCTION breaking of cell membrane 0 Burst size of viruses released from one infected cell Virus life 1Vira genome enters host cell 2Genome is transcribedtranslated viral proteins are also produced 3Genome is replicated use host s enzymes 4 Particles assemble inside host 5Partices exit usually lysis in 1000 s a lot 6 Free particles transmitted to new host g Temperate lysogenic viruses 0 AKA the sneaky ones 0 Maintained in latent stage dormantquiescent 0 Viral genome integrates into host cell DNA prophage so each time cell divides copies of viral genome are made 0 Then triggered by stress exits DNA and continues in lytic cycle 0 Called latency animal viruses or lysogeny bacterial 0 Possible outcomes of viral infection in animals o Lysis 0 Cancer 0 Persistent infection slow release without actually killing the cell 0 Latent infection present but not replicating triggered by stimulus then enters lytic infection A o Syncytium cell fusion Quantifying Viruses The Plaque Assay 0 Pour bacteria mix into Petri dish with nutrients let solidify incubate 0 Result plaques ready to be studied 0 O o Fundamental Components of Cell bacteriaarchaea Cell Envelope external Cell Membrane Cytoplasmic Contents internal 0 o Cytoplasmic Contents internal Denselypacked cell Structural complexity although not as complex as Eukaryotes o Chromosome nucleoid Ribosome Cytoskeleton Plasma Membrane Cell Wall Glycolipids o Flagellum The Nucleoid where DNA is o In direct contact with cytoplasm advantage bc that39s where transcriptionenzymes are 0 Highly structured supercoiled with additional coiling besides DNA helix 0 Structuremaintained by histoneIike proteins and topoisomerase enzymes Histonelikefor bacteria Archaea and Eukaryotes have actual histone proteins 0 Maintaining structureESSENTIAL Cytoskeletal Proteins o Foundall domains 0 Scaffolding structuresdense network of brous proteins 0 Structure and other functions 0 Protein amentsdynamic assembledisassemble Cytoplasmic Inclusions PHA o PHA poyhydroxyakanoates bacterial plastics o Pseudoorganelles bacteria don39t have quottruequot organelles of Eukaryotes 0 Excess chemicasstored in PHA bioplastics Cytoplasmic Inclusions Gas Vesicles 0 Found in aquatic cyanobacteria o Balloons give ce buoyancyin order to get to sunlightfood 00000 O o The Cell Membrane De nes cellthin phospholipid bilayer with proteins Hydrophobic insidefatty acids tail Hydrophilic outsideheads Amphipathic Structure Bacterial and Eukaryal Phospholipids Polar head loyal o Linked by EST 39 39 o Nonpolar tail hydroph o Phospholipids can vary fatty acid side chains candifferent le 0 and different degrees of saturation polar heads can va 0 FAME Fatty Acid Methyl Ester analysis for bacterial identi cat Archaeal Lipids o Differ in structure glycerol backbone esterlinkedisoprenoid lipids polar head group 0 Different types of lipids and different with ester links Lipid composition determines membrane properties 0 Saturated fats Rigid densely packed o Lipid Bilayer with no unsaturated fats lower permeability less uid 39 o o Unsaturated fats exible o Lipid Bilayer with many unsaturated fats higher gt permeability uid Cell membrane functions 1 Permeability barrier prevents leakagegateway for transport nutrients 0 General rule very few molecules go through layer without help o ng o 0 Small polar molecules 0 Small Polar uncharged molecules Permea 0 Large Polar uncharged molecules glucose 0 lons H Lo 0 o 2 Protein Anchor site of many proteins Transport across membrane bioenergetics and chemotaxis Transport across barriercels can accumulate nutrients Eukarya also use vesicles but bacteria and archaea only have proteins Active transport systems Composed of proteins Require energy 0 Are speci c o o 3 kinds of active transport systems Simple Transport Group Translocation ABC Transporter Proton Motive Force uses Chemical Modi cation of ATP hydrolysis movement of protons transported substances driven Periplasmic binding proteins by phosphoenolpyruvate and energy from ATP 0 Secretion systems for proteins diversity 0 Ex somesyringelike in order to inject proteins into other cells Efflux Pumps 0 Move small molecules out of cell 0 Usually nonspeci c o AKA multidrug exporter ex transport antibiotics 3 Energy Conservation Site of generationuse of proton motive force gradient of ions across cell membrane 0 o The Cell Envelope external Cell wall Surface layers Cell capsules Protein appendages Motility features Environment surrounding cell 0 A Dilute aqueous environment Feral with few solutes lots of water H399 y Cell 39 concentrated Turgor pressure is great water 0 0 High pressure 0 environment 0 If you put a cell in a dilute aqueous environment the cell would expand and lysis ow of water molecules go from the dilute lots of water environment to the highly concentrated little water cell Possible solutions 0 Pump water out 0 Have a cell wall most common 0 Live in isotonic environments 0 Cell Wall in Bacteria 0 Made of peptidoglycan o GramStain correlates with cell wall structure Grampositive staining bacteria stain purple because of thick peptidoglycan layer outside of cytoplasmic membrane Gramnegative staining bacteria stain pink because have outer membrane on top of having a thinner peptidoglycan layer 0 Peptidoglycan Single molecule Elastic strong ONLY BACTERIA Porous Provides protection from lysis shape involved in cell division Main components 0 M N acetylmuramic acid sugars make carbon backbone G N acetylglucosamine peptide bridges connect them How is it assembled Everythinginside cell but is built outside in cytoplasm Makes one building block one G one M one peptide inside hook it to lipid carrier bactoprenol and diffuses across membrane Transglycosylases and transpeptidases break existing peptidoglycan so can add the new subunits When we want to stop the spread of bacteriawe target peptidoglycan Lysozyme enzyme in our ears skin saliva etc degrades peptidoglycan o Grampositive cell envelope Thicker layer of peptidoglycan Dyes purple with gram stain Glycopolymers Teichoic acids important for cell shape cell division pathogenesis and antibiotic resistance 2 types lipoteichoic lipids and wall teichoic Linking proteins 0 Attached to cell wall involves enzymes called sortases that connect them to peptidoglycan o Gramnegative cell envelope More complex than gramnegative bacteria Thinner peptidoglycan layer Dyes pink with gram stain Have extra membrane Outer Membrane which is structurally and compositionally different than cytoplasmic membrane 0 Inner half typical phospholipids Outer half different molecule lipospolysaccharide Permeability barrier tend to be more resistant to antibiotics than gramneg bacteria 0 Contains porins channel proteins hollow tubes nutrients Periplasm additional space between membranes because of extra outer membrane 0 Lipopolysaccharide endotoxinLPS Great structural diversity o Ospecific polysaccharide core polysaccharide Lipid A o KDO Detodeoxyoctanoic Acid only found in LPS in the core Can be toxic to animals 0 Summary 0 Peptidoglycan generally thin if thicker layer then the o bacteria grampositive 0 Outer Membrane contains LPS and porins o Periplasm uniaue compartment with peptidoalvcan Not all bacteria have a cell wall 0 Mycoplasma lack cell wall restricted to living within animals some are human pathogens 0 0 Outside the Cell oPili and Fimbrae 0 Protein laments 0 Movement 0 Attachment help bacteria attachother cells 0 Protection 0Capsules aka slime glycocalyx 0 Usually polysaccharide Hydration Protection from phagocytosis Attachment May allow some bacteriabe diseases 0 Hydrophilic Flagellum o Motility rotary motoruses protons to drive rotation 0 Larger than pili 0 Attachment 0 Made of basal body connects freemoving Different bacteria different uses of agellum Ex some use all agellum grouped together in counter clockwise motion 0 Some use agellum individually in clockwise motion Liquid swimming Solid swarming often hyper agellated Without agella gliding or twitching pili Taxis directed movement Bacteria move towards light oxygenproducing cell etc to cell hook lament O 0000 0 Commercial Uses of Polvsaccharides Xanthum gum 0 Highly viscous even at low concentration and tolerant to variations in pH temperature electrolytes etc 0 Food industry use jams sauces icings 0 Industrial use explosives textiles paints o Pharmaceuticals and cosmetic use gt Produced by naturally occurring bacteria 0 0 Comparison Archaea and Bacteria Structurally similar prokaryotic cell structure organelles Some archaea have histones package DNA vs bacteria have histonelike proteins Archaea cell membranes have etherlinked lipids vs bacteria have esther bonded lipids Most archaea have cell wall but never peptidoglycan vs bacteria have peptidoglycan Archaea have several different cell wall types 0 0 Differences between Eukaryotic and Prokaryotic Cells Nucleus membranebound in eukaryotes Volume 0 Eukaryotes bigger advantage have more stuff but then have to move a lot too Organelles and internal membrane systems Trafficking inside cell via cytoskeleton External structures fungalplant cell wall and animal extracellular matrix 0 0 Recognition of Microbial Structures PRP Pattern Recognition Protein MAMP Microbe associated molecular pattern Cells phagocytes have PRP to recognize bacteria structures We have different proteins for different recognition of microbes Microbes can vary MAMPs to avoid recognition by immune system