Microbiology Quiz 2 PowerPoint s 3 5 4 LECTURE 3 5 Gram positive envelope o Up to 30 layers o Crosslinks 9 abnormal amino acids long o Teichoic acids give strength and negative surface charge Carbohydrate chains and D alanine attach to NAM Lipoteichoic acids anchor to cytoplasmic membrane o No periplasm o 2 groups of gram positives 1 Firmacutes ex Bacillus Low G C 2 Actino Bacteria ex Streptomyces High G C o Gram positive retains the violet dye because the cell envelope is so thick Gram negative envelope o More complex and common than Gram o Thin peptidoglycan layer o Crosslinks 4 amino acids longs o Thick periplasm o Peptidoglycan is in periplasm between the two membranes Cytoplasmic membrane inner Outer membrane o Outer layer has an odd construction Lipid bilayer outer leaflet is lipopolysaccharide LPS layer not phospholipid Barrier to many molecules small molecules ions pass through channels called porins O antigens are used for recognizing organisms like a fingerprint Our body recognizes the O antigen and therefore that there s a gram negative organism present immune system trigger Outer leaflet carries a long molecule called lipid A Anchors LPS molecule in lipid bilayer Large amounts Ex Gram negative infection of bloodstream immune In small amounts protective role in recognition of infection response is massive and damaging toxic shock death toxin is not secreted but is a structural part of gram negative Endotoxin bacteria LPS of the outer membrane of gram negative cells are toxic breaks down peptidoglycan which is found in eggs tears block the transpeptidase cross linking enzyme so D Lysozyme enzyme and saliva alanine 2 is not released Beta lactam antibiotics o Beta lactam has an unusual four member ring o Ways microbes resist beta lactams 1 Beta lactamase 2 Transpeptidase mutation Would need to be in the gene s that codes for the amino sequence of o 1 Bacterial Transformation free DNA can be taken up and incorporated the transpeptidase enzyme Types of Gene transfer into a recipient organism Horizontal gene transfer is an example o 2 Conjugation cell to cell transfer of DNA o 3 Transduction virus to virus DNA transfer Vancomycin is a drug that targets peptidoglycan o Treats C diff and MRSA Some bacteria have no cell walls Mycobacterial envelopes have mycolic acid long uncharged chains made of waxy materials o Lipids that give an impermeable layer around the bacterial cells o Protects them from immune defenses macrophages o Protects from antibiotics The nucleoid forms about 50 loops or domains Within each domain the DNA is super coiled by DNA binding proteins o DNA is negatively super coiled twists are counterclockwise and separating Special structures of Phototrophs highly folded membranes harvest energy in chloroplasts polyhedral bodies packed Rubisco enzyme system for CO2 o Thylakoids o Carboxysomes o Gas vesicles o Storage granules fixation using this energy Glycogen PHB and PHA granules Stored energy sources Biodegradable plastics buoyancy Sulfur granules Energy source S oxidation o Magnetosomes Membrane embedded crystals of Fe3O4 fixation magnetite Orient the swimming of magnetotactic bacteria or fimbriae straight protein filaments composed of pilin monomers Appendages for cell attachment o Pili o S ex pili o S talks membrane involved in conjugation embedded extensions of the cytoplasm Tips secrete adhesion factors called holdfasts connect cells and act as conduits part of biofilms o Nanotubes Flagella o Peritrichous flagella are randomly distributed around the cell o Lophotrichous o Monotrichous o Rotated by a molecular motor driven by the proton motive force PMF flagella at both ends of cells a single flagellum counter clockwise rotation causes flagella to bundle together clockwise rotation that causes the flagella bundle to come apart o Repellents o Attractants movement in response to chemical gradients Chemotaxis and push the cell forward to run and the cell tumbles stops and then changes direction alternating runs and tumbles prolonged o Random walk o Biased random walk caused by attractant concentration increase with run LECTURE 4 Colony on a plate is not homogenous Microbial growth in a liquid medium o Growth is homogenous o Shaken in order to allow aerobes access to oxygen and allow it dissolve into the liquid and increase dissolved oxygen Microbes in nature are generally starving or competing intensely for nutrients o Due to limited supplies in their habitats o Have to scavenge for their food o Heavy competition even in your intestinal flora All living cells require o 1 Macronutrients in large quantities I Carbon hydrogen nitrogen oxygen phosphorus sulfur CHNOPS CHNOPS monomers macromolecules II Potassium magnesium calcium and iron Enzyme cofactors signaling molecules etc o 2 Micronutrients in tiny amounts Co Zn Cu Mo Ni Mn trace elements Largely enzyme cofactors o 3 Growth factors not all Depends on ecological niche Bacteria typically live in mixed communities consortia where each group provides growth factors to others Prokaryotes have evolved to take advantage of a vast range of nutrients depending on o Niche where they get nutrients o Amounts needed o Chemical forms they can use inorganic organic Types of medium o 1 Defined Minimal chemical composition of all components is known Specific carbon source Specific nitrogen source Specific sulfur source Salts o 2 Rich Complex complex components Yeast extract or Meat extract Tryptone enzyme digested casein Salts 2 ways that CO2 gets fixed o 1 Through bacteria and plants that photosynthesize o 2 Through bacteria and plants that use lithotrophy Energy photoautotrophs sunlight Carbon CO2 cyanobacteria photoheterotrophs sunlight organic compounds Carbon cycle glpF italicized or underlined gene GlpF protein gene product o Requires both autotrophs and heterotrophs purple nonsulfur o CO2 fixed into biomass autotrophs heterotrophs C is released in CO2 CO2 etc sugars aa s two solutes transported at the same time maintenance of a relatively stable internal environment o Bacteria must maintain homeostasis by using various transporters Homeostasis Symport Siderophores Antiport The ABC Transporter Superfamily iron scavenging molecules that carry iron ATP Binding Cassette ABC transporters o Example LacY permease for both lactose and H one solute enters the cell while other exits chemoautotrophs o Vital for homeostasis which uses active transport inorganic CO2 o Iron is an important cofactor vent bacteria o Example