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2011-04-01 19:31:13
Cell structure function

Bacterial Cell Structure and Function
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  1. Bacterial Morphologies:
    • 1. Baccillus - rod shaped
    • 2. coccus - spherical
    • 3. Vibrio - curved or comma shaped
    • 4. Spirochete - helical
    • 5. Pleomorphic - can be more than one shape
  2. Cell Clustering:
    • 1. diplo - linking of cells in twos
    • 2. tetra - linking of cells in fours
    • 3. staphylo - clusters like grapes
    • 4. strepto - chains like a necklace
  3. Function of cell membrande: (cytoplasmic membrane)
    -defines the inside and outside of cell

    -contains protein transporters that pump desirable chemicals into the cell using the cells energy resources

    - prevents undesirable chem from entering the organism
  4. Structure of peptiglycan:
    -like a fish net because the long polymers of glycan are cross-linked by shorter pieces of peptides
  5. Two biologically active items that destroy the bacterial cell wall
    • 1. lysozyme
    • 2. penicillin
  6. Structural component unique to gram-neg bacteria = outer (extra) membrane
    - outer membrane has lipopoly saccharide attached to it

    • Lipid A = endotoxin
    • - potent inducer of inflammatory reactions

    • Gram (-) has only a few layers of peptidoglycan (red)
    • Gram (+) has several layers (violet)

    • The cytoplasmic membrane is the same
    • The outer membrane is different because only gram (-) bact have one
  7. 4 Steps of a Gram's stain:
    • 1. Stain w/primary stain, crystal violet
    • 2. Fix crystal violet w/Gram's iodine so it aggregates
    • 3. Wash the aggregates from porous gram (-) w/ acetone-alcohol
    • 4. Counter stain w/safranin so gram (-) cells are visible
  8. Polysaccharide: is the coating's chem makeup (coats bacterium)
    this coating make the bacterium slippery so WBC's cannot attach and destroy it
  9. Cell cytoplasm:
    - contains all the degradative and synthetic machinery to allow the cell to grow and make new copies of itself

    - it includes DNA, RNA and proteins
  10. Difference between bacterial chromosome and plasmids:
    - Bact chromosome contains thousands of genes including those required for replication and gene expression

    - Some bacteria contain plasmids, small pieces of DNA usually encoding fewer than fifty genes

    - Plasmids are often specialized (like those that code for resistance to a specific antibiotic)
  11. Bacterial Ribosome:

    Prokaryotic ribosomes are 70s (30s & 50s)

    Eukaryotic ribosomes are 80s (40s & 60s)
    -Some bacteria harbor inclusions or granules, which provide an energy source available for when cells have a special energy need

    - Granules, or inclusions are composed of polysaccharides or polyphosphates that contain chem energy
  12. Spores:
    - Most stable life form

    - Genera producing spores include the gram-positive Clostridium and Bacillus
  13. Streak plate
    - A dish containing nutrient agar

    - Used to grow individual cells into colonies to obtain pure isolates
  14. Colony:
    - Results when a single cell is streaked onto a plate in a ewll-separated manner so that the progeny can grow into a clump until they are sufficiently numerous to be seen by the naked eye

    - Obtain isolated colonies because they yield pure cultures in which every cell in identical, so organisms can be recognized
  15. Methods used to ID bacteria:
    • 1. Biochemical tests
    • 2. Immunological tests
    • 3. Genetic tests
    • 4. Direct DNA or RNA testing for organism-specific sequences
  16. Bacterial appendages and functions:
    • 1. flagella - aid in motility
    • 2. pili - aid in gene transfer
    • 3. fimbriae - attach to a given site (hold fast)
  17. 3 Major conponents of bacterial flagella:
    • 1. filament
    • 2. hook
    • 3. basal body
  18. Bacteria produce a probelling force by rotating their helical filaments against their watery environment.
  19. 2 Benefits of motility to pathogenic organism
    1. allow pathogens to spread

    2. allow pathogens to escape capture by cells immune system
  20. Chemotaxis:
    allow organisms to swim toward or away from chemicals