Block One Text 7

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Block One Text 7
2014-09-25 08:47:08
Test One
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  1. Major function of cell wall?
    • a.       prevent bacterial cells from rupturing when the water pressure inside the cell is greater than that outside the cell
    •                                                               i.      It also helps maintain the shape of a bacterium and serves as a point of anchorage for flagella
  2. a.       Composition
    Bacterial cell wall
    •                                                               i.      composed of peptidoglycan, which consists of a repeating disaccharide attached by polypeptides to form a lattice that surrounds and protects the entire cell
    • 1.       The disaccharide portion is made up of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), which are related to glucose
  3. 1.       Alternating __ and __ form __; andjacent rows are linked by polypeptides
    a.       It always includes __, which consist of __ attached to NAMs in the backbone
                                                                                                                                          i.      The amino acids occur in alternating patter of __ and __
                                                                                                                                        ii.      __ may be directly bonded to each other or linked by a __, consisting of a short chain of amino acids
    • NAM and NAG form backbones
    • tetrapeptide side chains
    • four amino acids
    • D and L forms
    • Parallel tetrapeptide side chains
    • peptide cross-bridge
  4. 1.       Penicillin interferes with the __
    a.       As a result, the cell wall is greatly weakened and the cell undergoes __, destruction caused by rupture of the plasma membrane and the loss of cytoplasm
    • final linking of the peptidoglycan rows by peptide cross-bridges
    • lysis
  5.                                                               i.      Gram-Positive Cell Walls
    1.       Have many layers of __, forming a thick, rigid structure
    a.       Gram-negative only contain a __
    2.       Cell walls of gram-positive bacteria have __, which consist primarily of an alcohol and phosphate
    a.       __: spans the peptidoglycan layer and is linked to the plasma membrane
    • peptidoglycan
    • thin layer of peptidoglycan 
    • teichoic acids
    • Lipoteichoic acid
  6. a.       __: linked to the peptidoglycan layer
                                                                                                                                          i.      Negativeà __ 
                                                                                                                                        ii.      May assume a role in __, preventing extensive wall breakdown and possible cell lysis
                                                                                                                                      iii.      Teichoic acids provide __ and thus make it possible to __
    • Wall teichoic acid
    • bind and regulate the movement of cations into and out of cell
    • cell growth
    • much of the wall’s antigenic specificity
    • identify gram-positive bacteria
  7.                                                               i.      Gram-negative Cell Walls
    1.       The cell walls of gram-negative bacteria consist of __
    2.       Peptidoglycan bonded to __in the outer membrane and is in the __

    3.       Don’t have __ and more can break down easier
    4.       Outer membrane has __, __, and __
    one or a few layers of peptidoglycan and an outer membrane


    periplasm (between outer and plasma membrane with high concentration of degradative enzymes and transport proteins)

    teichoic acids

    lipopolysaccharides, lipoproteins, and phospholipids
  8. 1.       Functions in gram negative cell walls
    • a.       Strong negative charge is important in evading phagocytosis and the actions of complement, two components of the defenses of the host
    • b.      The outer membrane provides a barrier to certain antibiotics, digestive enzymes, detergents, etc. 
  9. 1.       Outer membrane not a barrier to all substances in the environment because nutrients pass through to sustain the metabolism of the cell
    2.       Permeability due to __that permit passage of molecueles 
  10. 1.       LPS of the outer membrane is a large complex molecule that contains lipids and carbs and consists of three components: __(3)__
    1) lipid A, 2) a core polysaccharide, 3) an O polysaccharide
  11. Lipid A
    a.       lipid portion of LPS embedded in top layer of outer membraneà death of bacteria leads to release of Lipid A, which acts as an endotoxinè fever, shock, etc
  12. The core polysaccharide 
    a.       The core polysaccharide is attached to lipid A and has unusual sugarsè provide stability
  13. O polysaccharide 
    a.       O polysaccharide extends out from core polysaccharide and composed of sugar molecules; acts as antigen and is useful for distinguishing species of gram-negative bacteria
  14.  a.       Alcohol does what to gram-positive cells to make it __
                                                                                                                                          i.      Gram negative cells: alcohol does what?
    • dehydrates peptidoglycan 
    • more impermeable to the CV-I
    • dissolves the outer membrane and leaves small holes in the thin peptidoglycan layer through which CV-I diffusesà colorless
  15.                                                               i.      Atypical Cell Walls
    1.       Certain types of cells have no walls or very little material
    a.       ___ are the smallest known bacteria that grow and reproduce outside living host cels
    b.      Because of size and no cell walls, they pass through most bacterial filters
    c.       Their plasma membranes have __
    • Mycoplasma 
    • lipids called sterols to prevent lysis
  16. 1.       Archaea may lack walls or may have unusual walls composed of polysaccharides and proteins but not peptidoglycan
    a.       No peptidoglycan, but instead __, which contains __ instead o NAM and lacks the __found in bacterial cell walls

    N-acetyltalosaminuronic acid

    D-amino acids
  17. 1.       Acid Fast Cell Walls
    a.       Acid fast is used to identify __ and __
                                                                                                                                          i.      These bacteria have high concentrations of a hydrophobic waxy lipid (__) in their cell wall that prevents the uptake of dyes, including those used in the Gram stain
    1.       The __ and __ are held together by a polysaccharide
    2.       The hydrophobic waxy cell wall causes both cultures of Mycobacterium to clump and stick to the walls fo the flask
    Mycobaterium and pathogenic species of Nocardia

    mycolic acid

    mycolic acid and peptidoyglycan
  18. 1.       Lysozyme: __
    a.       The cellular contents that remain surrounded by the plasma membrane may remain intact if lysis does not occur; this wall-less cell is the __, whcihis usually spherical and capable of metabolism
    b.      In gram negative, some __; the cellular contents, plasma membrane, and remaining outer wall layer are __
    c.       To work, gram negative are first treated with __, which __, allowing the lyzosyme to destroy peptidoglycan layer
    catalyzes hydrolysis of the bonds between the sugars in the repeating disaccharide “backbone” of peptidoglycan


    outer membrane remains



    weakens ionic bonds in the outer membrane and damages it,
  19. 1.       Penicillin:__

    a.       Gram negative are not as susceptible to penicillin, but __penetrates the outer layer better than penicillin
    2.       Osmotic lysis
    • may cause some sell walls to swell into irregularly shaped cells called L forms
    • beta-lactam