Outer structure of bacteria

Outer structure of bacteria

1. Glycocalix

   • Substance that sorrunds cells
     • Secreted to the cell surface
       • Extracellular polymeric substance
   • Polymer that is external to the cell wall
     • Composed of polysaccharide , polypetide or both
       • Considered a capsule
         • Protects the bacteria of phygocytosis
       • Bacterial virulence

2. Flagella

   • Long filamentous appendages
     • Helical structure with diferent rotations
       • Cell generation of energy activates the rotations
       • Bacterial cell can alter the speed annd direction
   • peritrichous
   • Polar
     • monotrichous lophotrichous amphitrichous
       • H-antigen
         • Used to detect seovars
   • Parts
     • Filament
       • Diameter woth globular protein
     • Flagellin
       • Chains forming a heilix
     • Basal Body
       • small rod inserted in rings

3. Axial Filaments

   • Boundles of fibrils
     • arise at the end of the cell
     • Rotations
       • Produces movement of the outer seath
       • Corckscrew motion
   • Similar to flagella
     • with more mobility

4. Fimbriae and Pili

   • Fimbriae
     • Used to transfer DNA
     • Trend of adhesion
     • form biofilm
   • Pili
     • Protiens of the structure of fimbriae
     • Mobility
     • DNA transfer
     • longer
       • 1-2 p/cell

5. Cell Wall

   • Complex
     • Gives protection
   • Semirigid
     • Prevents rupture in the cell
   • Gives shape
   • 2 types
     • gram-negative
       • 1 layer
         • peptidoglycan
         • Outer membrane
       • no techioic acids
       • Consists
         • lipopolysaccharides
         • lipoproteins
         • phospholipids
     • gram-positive
       • many layers
         • peptidoglycan
       • contain teichoic acid
         • cell growth
         • negative charge
       • covered with
         • polysaccharides

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