MMG301 1nd EditionExam # 2 Study Guide Lectures: 10-21Lecture 10 -eukaryote: an organism with a membrane enclosed nucleus and other organelles-mitochondrion: site of respiration-chloroplast: site of photosynthesis-endosymbiosis: an organism engulfs another organism and over time, gains the function of the organism it engulfed-mitochondria and chloroplasts originated by endosymbiosis-protists: unicellular and colonial microbial eukaryotes other than fungi-protozoa: unicellular heterotrophic protists-evolution-reductive: loss of a function-convergent: similarities evolved independently by different groups-mitochondrion: performs respiration and oxidative phosphorylation as source of energy-hydrogenosome: a degenerate mitochondrion; formed by reductive evolution; performsoxidation of pyruvate as a source of energy; unable to perform the citric acid cycle (CAC) because it lacks the necessary enzymes-fungi-cell walls contain chitin, which is a little bit different than cellulose, so that fungi is able to break down organisms with a cell wall composed of cellulose-use absorptive nutrition: secrete digestive enzymes and absorb broken-down molecules-come in various forms-filamentous, unicellular, and mushrooms-decompose and mineralize organic carbon-for example: they are the only organism that can degrade wood-dominate the microbial biomass in soilLecture 11-major components of a bacterial cell-cell envelope: keeps cell intact, is a selective transport barrier-surface appendages: various functions-internal matrix: cytoplasm, nucleic acids and other elements-gram positive bacteria-very thick cross linked peptidoglycan-no outer membrane-gram negative bacteria-thin peptidoglycan within a periplasmic space-outer membrane-gram negative cell envelope-cytoplasmic membrane-phospholipid bilayer and various proteins-outer membrane-inner leaflet: phospholipids and proteins-outer leaflet: lipopolysaccharide (LPS), phospholipids and proteins-periplasm-functions of the LPS-major structural component of the OM -lipid A: essential for the formation, stabilization, and function of the OM, thus viability and growth of the cell-toxicity to animals: (LPS = endotoxin). Responsible for a number of bacterial illnesses like salmonella -localization of specific proteins to the OM; these proteins function in close association with LPS -protection against entry of certain toxic extracellular substances into the cell -specificity of recognition: O-specific polysaccharide recognized by bacteriophages and by immune system of warm-blooded animals; can protect from phagocytosisLecture 12-surface layers (S)-outermost layer of the cell envelope-completely covers the cell-protective coat with uniform porosity-the cytoplasmic membrane-phospholipid bilayer-ester linkage in bacteria and eukarya-ether linkage in archaea (hint: ether and archaea both have h’s in them, just a trick to help you remember)-integral membrane proteins-outer face (OF): exposed to periplasm-inner face (IF): exposed to cytoplasm-transmembrane proteins (T): span the entire lipid bilayer (hence the name trans membrane)-fluid membrane: allows lateral movement of proteins-functions of the bacterial cytoplasmic membrane-permeability barrier: prevents leakage into or out of the cell; serves as a gateway for nutrient transport into or out of the cell-protein anchor-energy production: site of generation and use of the proton motive force (where ATP is synthesized)-nutrient transport across the cytoplasmic membrane-simple transporter: single membrane protein-group translocation: series of proteins; solute is phosphorylated during transport-ABC transporter: three or more proteins; process involves consumption of ATP-cell walls of archaea-not made of peptidoglycan-no outer membrane-three main types of cell walls1. S layer (most common)2. psuedomurein (pseudo – peptidoglycan) (in certain methanogens)3. other polysaccharidesLecture 13-bacterial glycocalyx: matrix of polysaccharides and/or glycoproteins outside the bacterial cell-capsule-slime layer-functions: water retention, protective barrier, promotes cell aggregation/ flocculation, adhesion, pathogenesis (evasion from phagocytosis), biofilm formation-bacterial motility-dispersal: when bacteria grow to large enough numbers, they are too concentrated and need to spread out due to…-nutrient limitation-accumulation of waste-to escape predatory or host defense activities-types of dispersal (for prokaryotes)-flagella rotation-gliding motility (gliding and twitching do not involve flagella)-flexing periplasmic axial filament-gas vesicles: passive dispersal by buoyancy; watertight, gas permeable internal structures made by some aquatic microbes -bacterial flagella-monotrichous polar: singular flagellum at one end-monotrichous lateral: singular flagellum in the middle-lophotrichous: tuft of flagella at one cell pole-amphitrichous: tufts of flagella at both cell poles-peritrichous: flagella located all over the cell-structure of bacterial flagella-filament: functions as propeller-hook: transfers rotation-basal body: motor-movement of flagellated bacteria-counterclockwise: flagella concentrate at one cell pole and propels the bacteria forward-clockwise: flagella relax and bacteria tumbles randomlyLecture 14-nucleoid-DNA plus a few specialized proteins-gyrase and topoisomerase-histone-like proteins-bacterial ribosomes-synthesize proteins-polysomes-internal membranes-invaginations-vesicles-stacked thylakoids in cyanobacteria-anammoxosomes (in anammox bacteria)-surrounded by a lipid bilayer-carboxysomes: compartments surrounded by a protein shell-magnetosomes-invagination of cytoplasmic membrane-cytoskeletal filaments-create a magnetic dipole-magnetotaxis-gas vesicles-in some aquatic bacteria-membrane is made of proteins-position the photosynthetic and heterotrophic bacteria in the photic zone-permeable to dissolved gases-not permeable to water and solutesLecture 15-70-80% of microbial cell mass is water-95% of dry cell weight is macroelements-C, H, O, N, S, P, K, Mg, Ca-carbon is need in the largest amount-nitrogen is the second largest-inorganic nutrients:-inorganic macronutrients: K, Mg, P, S, Ca – needed for many cell processes-inorganic micronutrients: Cr, Co, Cu, Mo, Zn, others-synthetic (defined) medium: component molecules are known-minimal medium: contains only those ingredients required for growth of a given organism-complex (undefined) medium: ingredients of undefined composition-selective medium
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