Microbiology

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Prokaryotes, Eukaryotes, etc.

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  • Membrane structures. Top, an archaealphospholipid: 1, isoprene chains; 2, ether linkages; 3, L-glycerol moiety; 4, phosphate group. Middle, a bacterial or eukaryotic phospholipid: 5, fatty acid chains; 6, ester linkages; 7, D-glycerol moiety; 8, phosphate group. Bottom: 9, lipid bilayer of bacteria and eukaryotes; 10, lipid monolayer of some archaea.
  • Microbiology

    1. 1. Prokaryotes andEukaryotes<br />
    2. 2. Classification of Organisms<br />
    3. 3.
    4. 4. Major Difference<br />
    5. 5. Bacteria<br />Bacteria are prokaryotic cells, the simplest of microbial cells. They consist of cell portoplasm contained within a retaining a structure or cell envelope.<br /><ul><li>prokaryotic
    6. 6. simple, single-celled organisms
    7. 7. distinct cell wals containing peptidoglycan layer
    8. 8. No true nucleus (only nucleoid)
    9. 9. free-floating DNA (some w/ plasmid)</li></li></ul><li>MORPHOLOGY<br />Prokaryotes exhibit a variety of shapes<br />Most common <br />Coccus<br />Spherical<br />Bacillus<br />Rod or cylinder shaped<br />
    10. 10. MORPHOLOGY<br />Prokaryotes exhibit a variety of shapes<br />Other shapes<br />Coccobacillus<br />Short round rod<br />Vibrio<br />Curved rod<br />Spirillum<br />Spiral shaped<br />Spirochete<br />Helical shape<br />Pleomorphic<br />Bacteria able to vary shape<br />
    11. 11. MORPHOLOGY<br />Arrangement:<br />Division along a single plane may result in pairs or chains of cells<br />Pairs = diplococci<br />Example: Neisseriagonorrhoeae<br />Chains = streptococci<br />Example: species of Streptococcus<br />
    12. 12. MORPHOLOGY<br />Arrangement:<br />Division along several random planes form clusters<br />Example: species of Staphylococcus<br />Division along two or three perpendicular planes form cubical packets<br /><ul><li>Example: Sarcinagenus</li></li></ul><li>
    13. 13. General Structure<br />
    14. 14. General Structure of a Prokaryotic Cell<br />
    15. 15. CELL APPENDAGES<br />
    16. 16. FLAGELLA<br />Some bacteria have protein appendages<br />Not essential for life<br />Aid in survival in certain environments<br />They include<br />Flagella<br />Pili<br />
    17. 17. FLAGELLA<br />Flagella<br />Long protein structure<br />Responsible for motility<br />Use propeller like movements to push bacteria<br />Can rotate more than 100,00 revolutions/minute<br />82 mile/hour<br />Some important in bacterial pathogenesis<br />H antigen useful in distinguishing among serovras of gram negative bacteria<br />
    18. 18. FLAGELLA<br />Flagella structure has three basic parts<br />Filament<br />Extends to exterior<br />Made of proteins called flagellin<br />Hook<br />Curved sheath<br />Connects filament to cell<br />Basal body<br />Anchors flagellum into cell wall and membrane<br />
    19. 19. Figure 4.8b<br />
    20. 20. FLAGELLAR ARRANGEMENTS<br />1. Monotrichous – single flagellum at one end<br />2. Lophotrichous – small bunches arising from one end of cell<br />3. Amphitrichous – flagella at both ends of cell<br />4. Peritrichous – flagella dispersed over surface of cell, slowest<br />
    21. 21. FLAGELLAR ARRANGEMENTS<br />
    22. 22. FLAGELLA<br />
    23. 23. Motile Cells<br />
    24. 24. Axial Filaments<br />Endoflagella<br />In spirochetes<br />Anchored at one end of a cell<br />Rotation causes cell to move<br />
    25. 25. PILI<br /> Rigid tubular structure made of pilinprotein<br />Found only in Gram negative cells<br />Functions <br />Sexual pili—joins bacterial cells for DNA transfer (conjugation)<br />Common pili—adhesion <br />
    26. 26. FIMBRAE<br />Fine hairlike bristles from the cell surface<br />Function in adhesion to other cells and surfaces<br />
    27. 27. CELL ENVELOPE<br />
    28. 28.
    29. 29. GLYCOCALYX<br />Coating of molecules external to the cell wall, made of sugars and/or proteins<br />2 types<br />slime layer - loosely organized and attached<br />capsule – highly organized, tightly attached<br />Functions<br />attachment<br />inhibits killing by white blood cells<br />receptor<br />
    30. 30. BIOFILM<br />Dental Plaque<br /><ul><li>A polysaccharide-encased mass of bacteria coating the surface of a tooth
    31. 31. Streptococcus mutansuses sucrose to synthesize a biofilm
    32. 32. Other bacteria can then adhere to the layer</li></li></ul><li>The appearance of colonies composed of encapsulated cells (mucoid) compared with those lacking capsules (nonmucoid). <br />Staining reveals the microscopic appearance of a large, well- developed capsule.<br />
    33. 33. CELL WALL<br />Bacterial cell wall <br />Rigid structure<br />Surrounds cytoplasmic membrane<br />Determines shape of bacteria<br />Holds cell together<br />Prevents cell from bursting<br />Unique chemical structure<br />Distinguishes Gram positive from Gram-negative<br />
    34. 34. GRAM POSITIVEGRAM NEGATIVE<br />
    35. 35. GRAM POSITIVE WALL<br />Rigidity of cell wall is due to peptidoglycan (PTG)<br />Compound found only in bacteria<br />Basic structure of peptidoglycan<br />Alternating series of two subunits<br />N-acetylglucosamine (NAG)<br />N-acetylmuramic acid (NAM)<br />Joined subunits form glycan chain<br />Glycan chains held together by string of four amino acids<br />Tetrapeptide chain<br />
    36. 36. GRAM POSITIVE WALL<br /><ul><li>Relatively thick layer of peptidoglycan
    37. 37. As many as 30
    38. 38. Regardless of thickness, peptidoglycan is permeable to numerous substances</li></ul>Teichoicacid component of peptidoglycan; composed of glycerol and phosphate<br />Lipoteucholic acid is attached to the lipids of cytoplasmic membrane<br />Gives cell negative charge<br />
    39. 39. GRAM POSITIVE WALL<br />
    40. 40. GRAM POSITIVEGRAM NEGATIVE<br />
    41. 41. GRAM NEGATIVE WALL<br />More complex than Gram+<br />Only contains thin layer of peptidoglycan<br />Peptidoglycan sandwiched between outer membrane and cytoplasmic membrane<br />Region between outer membrane and cytoplasmic membrane is called periplasm or periplasmic space<br />Gel-like area<br />Most secreted proteins contained here<br />
    42. 42. GRAM NEGATIVE WALL<br />Outer membrane <br /><ul><li>Connected to the peptidoglycan layer by lipoproteins
    43. 43. Constructed of lipid bilayer</li></ul>Much like cytoplasmic membrane but outer layer made of lipopolysaccharides and phospholipids<br />Outer membrane also called the lipopolysaccharide layer or LPS layer<br />LPS severs as barrier to a large number of molecules<br />Small molecules or ions pass through channels called porins<br />Specific channel proteins are present<br />
    44. 44. GRAM NEGATIVE WALL<br />O-specific polysaccharide chain<br />Directed away from membrane<br />Opposite location of Lipid A<br />Used to identify certain species or strains<br />E. coli O157:H7 refers to specific O-side chain<br />Lipid A<br />Portion that anchors LPS molecule in lipid bilayer<br />Plays role in recognition of infection<br />Molecule present with Gram negative infection of bloodstream--endotoxin<br />
    45. 45. GRAM NEGATIVE WALL<br />
    46. 46.
    47. 47. Gram-Positive Membrane<br />
    48. 48. Gram-Negative Outer Membrane<br />
    49. 49. CELL WALL<br />Peptidoglycan layer as a target<br />Many antimicrobial interfere with the synthesis of peptidoglycans or alter its structural integrity <br />Examples include<br />Penicillin<br />Lysozyme<br /><ul><li>Penicillin
    50. 50. Binds proteins involved in cell wall synthesis
    51. 51. Prevents cross-linking of glycan chains by tetrapeptides
    52. 52. More effective against Gram positive bacterium
    53. 53. Due to increased concentration of peptidoglycans
    54. 54. Penicillin derivatives produced to protect against Gram negatives</li></li></ul><li>CELL WALL<br />Lysozymes<br />Produced in many body fluids including tears and saliva<br />Breaks bond linking NAG and NAM<br />Destroys structural integrity of cell wall<br />Enzyme often used in laboratory to remove peptidoglycan layer from bacteria<br />Produces protoplast in G+ bacteria<br />Produces spheroplast in G- bacteria<br />
    55. 55.
    56. 56. CELL WALL<br />Differences in cell wall account for<br />differences in staining<br />Characteristics:<br />Gram-positive bacterium retain crystal violet-iodine complex of Gram stain<br />Gram-negative bacterium lose crystal violet-iodine complex<br />
    57. 57. The Gram Stain<br />
    58. 58. CELL WALL<br />Some bacterium naturally lack cell wall<br />Mycoplasma<br />Bacterium causes mild pneumonia<br />Have no cell wall<br />Antimicrobial directed towards cell wall ineffective<br />Sterols in membrane account for strength of membrane<br />
    59. 59. CYTOPLASMIC MEMBRANE<br />Cell (Cytoplasmic) membrane<br />Delicate thin fluid structure<br />Surrounds cytoplasm of cell<br />Defines boundary<br />Serves as a semi permeable barrier<br />Barrier between cell and external environment<br />
    60. 60. CELL MEMBRANE<br />Structure is a lipid bilayer with embedded proteins<br />Bilayer consists of two opposing layers<br />Layer composed of phospholipids<br />Each contains a hydrophilic phosphate head and hydrophobic fatty acid tail<br />
    61. 61. CELL MEMBRANE<br />Membrane is embedded with numerous protein<br />More that 200 different proteins<br />Proteins function as receptors, channels proteins, and transport proteins<br />Provides mechanism to sense surroundings<br />Proteins are not stationary<br />Constantly changing position <br />Called fluid mosaic model<br />
    62. 62. CYTOPLASM<br />
    63. 63. CYTOPLASM<br />Dense gelatinous solution of sugars,<br />amino acids, & salts<br />70-80% water<br />Serves as solvent for materials<br />used in all cell functions<br />
    64. 64. STRUCTURES WITHIN CYTOPLASM<br />Bacterial cells have variety of internal structures<br />Some structures are essential for life<br />Chromosome<br />Ribosome<br />Others are optional and can confer selective advantage<br />Plasmid<br />Storage granules<br />Endospores<br />
    65. 65. INTERNAL STRUCTURES<br />Chromosome<br />Resides in cytoplasm<br />In nucleoid space<br />Typically single chromosome: protein and DNA<br />Circular double-stranded molecule<br />Contains all genetic information<br />Plasmid<br />Circular DNA molecule<br />Generally 0.1% to 10% size of chromosome<br />Extrachromosomal<br />Independently replicating<br />Encode characteristic<br />Potentially enhances survival<br />Antimicrobial resistance<br />Tolerance to toxic metals<br />
    66. 66. INTERNAL STRUCTURE<br />Ribosome<br />Involved in protein synthesis<br />Composed of large and small subunits<br />Units made of protein 40% and ribosomal RNA 60%<br />Prokaryotic ribosomal subunits <br />Large = 30S<br />Small = 50S<br />Small than eukaryotic ribosomes<br />Difference often used as target for antimicrobials<br />
    67. 67. INTERNAL STRUCTURES<br />Storage granules<br />Accumulation of polymers<br />Synthesized from excess nutrient<br />Example = glycogen<br />Excess glucose in cell is stored in glycogen granules<br />Gas vesicles<br />Small protein compartments<br />Provides buoyancy to cell<br />Regulating vesicles allows organisms to reach ideal position in environment<br />
    68. 68. INTERNAL STRUCTURES<br />Endospores<br />Dormant cell types<br />Produced through sporulation<br />Theoretically remain dormant for 100 years<br />Resistant to damaging conditions<br />Heat, desiccation, chemicals and UV light<br />Vegetative cell produced through germination<br />Germination occurs after exposure to heat or chemicals<br />Germination not a source of reproduction<br />Common bacteria genus that produce endospores include Clostridium and Bacillus<br />
    69. 69.
    70. 70. Inclusions<br />Metachromatic granules (volutin) <br />Polysaccharide granules<br />Lipid inclusions<br />Sulfur granules<br />Carboxysomes<br />Gas vacuoles <br />Magnetosomes<br />Phosphate reserves<br />Energy reserves<br />Energy reserves<br />Energy reserves<br />Ribulose 1,5-diphosphate carboxylase for CO2 fixation<br />Protein covered cylinders<br />Iron oxide (destroys H2O2)<br />
    71. 71. Inclusions<br />
    72. 72. Archaea<br /> primitive prokaryotes<br />extermophiles<br />lacks peptidoglycan in their cell wall<br />ether-linked membrane lipids<br />
    73. 73. Phylogenetic Tree of Archaea<br />
    74. 74. Archaea Morphology<br />Basic Archaeal Shapes : At far left, Methanococcusjanaschii, a coccus form with numerous flagella attached to one side. At left center, Methanosarcinabarkeri, a lobed coccus form lacking flagella. At right center, Methanothermusfervidus, a short bacillus form without flagella. At far right, Methanobacteriumthermoautotrophicum, an elongate bacillus form. <br />
    75. 75. Archaea Morphology<br /> Membrane lipids<br />ether bonds link glycerol to hydrocarbon side chains<br />lacks fatty acids<br />side chains composed of repeating isoprene units<br />major lipid components: glycerol dietherand diglycerolteraether<br />lipid monolayer<br />
    76. 76. Archaea Morphology<br />
    77. 77. Archaea Morphology<br />Cell Wall<br />lacks outer membrane<br />pseudomurein: <br />N-acetylglucosamine + N –acetyltalosaminuronic acid<br />β-1,3 glycosidic linkage<br />L-amino acids<br />Polysaccharide cell walls<br />Methanosarcina: glucose, glucuronic acid, uronic acid galactosamine, and acetate<br />Halococcus: same as Methanosarcinacell wall + Sulfate ions<br />
    78. 78. Archaea Morphology<br />Cell Wall<br />S-layers: paracrystalline surface layers<br />proteins or glycoprotein arranged in various symmetries <br />Functions:<br />structural support<br />interface btwn cell and its environment<br />selective sieve<br />retain proteins near cell surface<br />
    79. 79. Archaea Morphology<br />Other Cell Walls<br />Natronococcus:haloalkalophilic species of Archaea<br />glycoprotein cell wall contains L-glutamate as a single type of amino acid linking glucose and glucose derivatives<br />
    80. 80. Archaea<br />Crenarchaeaota: most thermophilicarchaea are found in this group. They use sulfur compounds as electron donors or as acceptors. Not all are thermophilic.<br />Euryarcheota: methanogens, halophiles, thermophiles.<br />Korarcheota; found in hot springs. None have been grown in pure culture.<br />
    81. 81.
    82. 82. The hot springs of Yellowstone National Park, USA, were among the first places Archaea were discovered. At left is Octopus Spring, and at right is Obsidian Pool. Each pool has slightly different mineral content, temperature, salinity, etc., so different pools may contain different communities of archaeans and other microbes. The biologists pictured above are immersing microscope slides in the boiling pool onto which some archaeans might be captured for study. <br />
    83. 83. Salt-lovers : immense bloom of a halophilic ("salt-loving") archaean species at a salt works near San Quentin, Baja California Norte, Mexico. This archaean, Halobacterium, also lives in enormous numbers in salt ponds at the south end of San Francisco Bay; interested residents of this area should take the Dumbarton Bridge for the best views. <br />
    84. 84. Eukarya<br />Figure 4.22a<br />
    85. 85. Flagella and Cilia<br />Figure 4.23a–b<br />
    86. 86. Microtubules <br />Tubulin<br />Nine pairs + two arrangements<br />Figure 4.23c<br />
    87. 87. Cell Wall<br />Cell wall<br />Plants, algae, fungi<br />Carbohydrates<br />Cellulose, chitin, glucan, mannan<br />Glycocalyx<br />Carbohydrates extending from animal plasma membrane<br />Bonded to proteins and lipids in membrane<br />
    88. 88. Plasma Membrane<br />Phospholipid bilayer<br />Peripheral proteins<br />Integral proteins<br />Transmembrane proteins<br />Sterols<br />Glycocalyx carbohydrates<br />
    89. 89. Plasma Membrane<br />Selective permeability allows passage of some molecules<br />Simple diffusion<br />Facilitative diffusion<br />Osmosis<br />Active transport<br />Endocytosis<br />Phagocytosis: Pseudopods extend and engulf particles.<br />Pinocytosis: Membrane folds inward bringing in fluid and dissolved substances.<br />
    90. 90. Eukaryotic Cell<br />Cytoplasm membrane:Substance inside plasma and outside nucleus<br />Cytosol: Fluid portion of cytoplasm<br />Cytoskeleton: Microfilaments, intermediate filaments, microtubules<br />Cytoplasmic streaming: Movement of cytoplasm throughout cells<br />
    91. 91. Organelles<br />Membrane-bound<br />Nucleus: Contains chromosomes<br />ER: Transport network<br />Golgi complex: Membrane formation and secretion<br />Lysosome: Digestive enzymes<br />Vacuole: Brings food into cells and provides support<br />Mitochondrion: Cellular respiration<br />Chloroplast: Photosynthesis<br />Peroxisome: Oxidation of fatty acids; destroys H2O2<br />
    92. 92. Eukaryotic Cell<br />Not membrane-bound<br />Ribosome: Protein synthesis<br />Centrosome: Consists of protein fibers and centrioles<br />Centriole: Mitotic spindle formation<br />
    93. 93. Nucleus<br />Figure 4.24<br />
    94. 94. Endoplasmic Reticulum<br />Figure 4.25<br />
    95. 95. Ribosomes<br />80S<br />Membrane-bound Attached to ER<br />Free In cytoplasm<br />70S<br />In chloroplasts and mitochondria<br />
    96. 96. Golgi Complex<br />Figure 4.26<br />
    97. 97. Lysosomes and Vacuoles<br />Figure 4.22b<br />
    98. 98. Mitochondrion<br />Figure 4.27<br />
    99. 99. Chloroplast<br />Figure 4.28<br />
    100. 100. Endosymbiotic Theory<br />Figures 10.2, 10.3<br />
    101. 101. Endosymbiotic Theory<br />UN 4.1<br />

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