Midterm Notes.docx

8 Pages
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Department
Microbiology and Immun (Sci)
Course Code
MIMM 211
Professor
Benoit Cousineau

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Description
3 kingdoms of life Bacteria, Archaea, Eucarya. Common threads of life Growth, Metabolism, Motion, Reproduction, Response to stimuli. Lucretius and Fracastoro Suggested invisible organisms cause disease. Jansen Invents and develops first microscopes. Hooke First description and depiction of microorganism. Leeuwenhoek Discovered bacteria and protozoa. Spontaneous Generation Formation of living organisms from inanimate matters. Redi Fly larvae can only develop in meat that fly can reach. Needham Boiled broth then sealed it. Microorganisms appeared. Spallanzani Broth in flask then sealed and boiled. No microorganisms appeared. PasteurBoiled broth in flask, curved neck of flask so air can enter but no dust, no microorganisms appeared. Tyndall Showed dust carried microorganisms. Beliefs in the cause of diseases Supernatural forces, Poisonous Vapors, Imbalances between the four humors. Bassi Showed microorganism (fungus) can cause disease in silkworms. Berkeley Potato blight was caused by fungus. Lister Sterilized instruments with heat, phenol to prevent infections. Koch Demonstrated bacterium was causing anthrax. Koch’s Postulates The microorganism is present in every case of the disease, but absent from health organisms, the suspected microorganism must be isolated and grown in pure culture, the same disease must result when the isolated microorganism is inoculated into a healthy host, the same microorganism must be isolated again from diseased host. Agar and Petri Dish Used to develop microorganisms in the lab. Jenner Immunized people from smallpox using cowpox virus. PasteurFirst attenuated vaccine from pure culture of pathogen attenuated. Smith and Salmon Killed microbial cells effective as vaccines. BehringHumoral Immunity, antibodies produced in blood against toxin to be protective against infection. Metchnikoff Cellular Immunity, Phagocytes engulfing disease-causing bacteria and provide immunological protection. Winogradsky Oxidation of iron, sulfur, ammonia by soil bacteria for energy, transformation of carbon dioxide to organic matter. Beijerinck Isolated nitrogen-fixing bacteria and sulfate-reducing bacteria. Taxonomy Artificial classification of organisms, based on visible similarities. Phylogeny Natural classification of organisms, reflects evolutionary relatedness between organisms. Uses ubiquitous gene sequence to compare microorganisms. Haeckel’s Proposal Plants, Animals, Microorganisms. Chatton’s Proposal Eukaryotes and prokaryotes. Whittaker’s Proposal Monera, Protista, Fungi, Plantae, Animalia. Woese’s Proposal Bacteria, Archaea, Eukaryotes – equally distant, used 16S ribosomal RNA gene. Endosymbiotic theory of evolution Primitive eukaryotic cell engulfed an ancient prokaryote to create the first eukaryotic cell. Goals of Classification Stability, Predictability, Build larger groups, Study a member, learn about the group. Linnaeus’s scheme of classification Based on comparison of visible characteristics. Hierarchical scheme of classification Kingdom, Phylum, Class, Order, Family, Genus, Species. Name of bacterial species Lactococcus lactis (L. lactis), consists of genus name and epithet. Use of bacterial species naming Appearance, Habitat, Characteristic property, Scientist name. Characteristics used to separate bacterial species Biovars (Biochemical/Physiological differences), Morphovars (different morphology – shapes), Serovars (different antigenic properties) Sj Similarity coefficient, # similarities shared/# similarities compared, used to make dendograms Phage typing What bacteriophages can infect, bacteriophage has host range. Genomic characteristicsG+C content (melting point + density), DNA hybridization (single strands allowed to mix), sequencing genes give phylogenetic relationship. Major differences between prokaryotes and eukaryotes Eukaryotes have nucleus, organelles, size is 10x bigger, prokaryotic cells have cell wall of peptidoglycan. Shapes/Arrangements of cells Spherical Cells – Cocci, Rodlike – Bacilli, Spiral – Spirilla, Other – Irregular Arrangements of Cocci Streptococci (line of more than 2), tetrad (square), sarcinae (2 layers of squares), staphylococci (big mass of layered cocci) Arrangements of Bacilli Coccobacillus (circular bacilli), Streptobacillius (line of more than 2) Bacterial Colony Morphologies Form – Punctiform, Circular, Filamentous, Irregular, Rhizoid, Spindle, Elevation – Flat, Raised, Convex, Pulvinate, Umbonate, Margin – Entire, Undulate, Lobate, Erose, Filamentous, Curled Bacterial Cells vs Human Cells Surface Area to Volume ratio of prokaryotes larger than eukaryotes, faster growth. Epulopiscium FishelsoniGuest at fish’s banquet, found in gut of brown surgeon fish, large Thiomargarita Namibiensis Sulfur pearl of Namibia, found in ocean sediments, larger than E. fishelsoni. Nanochlorum Eukaryotum Green alga, smaller than a human cell but is a true eukaryote – nucleus, mitochondrion, chroloplast. Bacterial Envelopes Gram-negative – outer membrane, cell wall, cytoplasmic membrane, Gram- positive – cell wall, cytoplasmic membrane, Mycoplasma – cytoplasmic membrane. Cytoplasmic MembraneContains cytoplasm, regulates what comes in and out, made up of a fluid phospholipid bilayer, contains proteins (transmembrane and peripheral membrane proteins). Phospholipid Structure Structurally asymmetric, charged polar heads, nonpolar hydrophobic long lipid tails. Peptidoglycan Cell Wall Gives cell shape and rigidity, osmotic pressure, peptidoglycan composition. Very thick around gram-positive, thin around gram-negative. Peptidoglycan Cell Wall Anchoring Gram-positive has teichoic acid (structure) and lipoteichoic acid (anchorage). Gram-negative has cell wall anchored by lipoproteins. Outer membrane Gram-negative, acts as protective barrier and regulates molecules coming through, made up of a fluid phospholipid bilayer (inner layer – phospholipids, outer layer – LPS, endotoxin, phospholipids). Anchored to cell wall by lipoproteins. Capsule/Slime layer Protection, reservoir of stored food, site for waste disposal, helps keep shape and rigidity, prevents infection, aids in cell adhesion and motility. FlagellaMovement of bacterial cells, made up of protein polymer Pili/Fimbriae Thinner than flagella, adherence to surfaces, sex pili for mating. Arrangements of bacterial flagella Monotrichous – single flagellum, Amphitrichous – single flagellum at each pole, Lophotrichous – two or more flagella at pole/poles, Peritrichous – flagella all over surface. Taxis with flagella Bacterial movement. Counterclockwise – forward, Clockwise – tumbling Chemotaxis Directional movement towards specific chemical. Cytoplasm Site of metabolism, 90% water, nucleoid (irregular mass of DNA), ribosomes, inclusion bodies (storage, gaz, magnetosomes). Endospores Most resistant biological structures, no metabolism, state of survival induced by unfavourable growth conditions. Sporulation Divides into 2 unequal parts. Larger part engulfs smaller part – becomes forespore. Forespore matures to become an endospore – synthesis of protective thick wall, dehydrated, lysis of cell to release endospore. Germination Endospore to vegetative cell; water enters, endospore swells and ruptures coat, germ tube grows. Binary fission Divide near midpoint to form two daughter cells. Budding Forms bubble-like structure that comes out and separates from parent cell. Fragmentation Filamentous growth, extends from main outwards like branches. Asynchronous cultures Timing of cell division is random. Synchronous cultures Timing of cell division is fixed. Generation time Period for cell to enlarge, divide, and produce 2 daughter cells. All cells in population have same generation time. Lag phase Time for cells to adjust to new/fresh medium and start dividing. Exponential/Log phase Period where nutrients are not in limiting amounts and cells divide at maximum speed. Stationary phase Culture switches from log phase to stationary phase when nutrient concentration is limiting and toxic waste accumulates so cells divide slower. Death phase Nutrients completely consumed, cells stopped growing and starting to die, but not all cells die. Reasons for long Lag phase Inoculum taken from old culture, from rich medium to poorer one, from chemically different medium, from refrigerated cells, in cold medium. Chemostat Provides constant flow of nutrients, concentration of one of the nutrients is limited to reduce growth rate, some growing culture should be removed at the same rate of gr
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