The Cell Wall

The Cell Wall

1. prevents osmotic lysis and protects cell membrane

2. Shapes the cell

3. Prokaryotes

   • made of peptidoglycan
     • Glycan Portion
       • Sugar
     • polymer of a repeating disaccharides
     • N-acetyglucosamine
       • NAG
     • N-acetylmuramie
       • NAM
         • four amino acids attacted
           • linked by a peptide cross-bridge
             • target of penicilliums
     • B-1, 4 linkage

4. Gram +

   • Purple
   • Thicc Peptidoglycan
   • polymers of glycerol or ribitol phosphate
   • wall teichoic acid
     • connects to the peptidoglycan
     • provide antigenic specificity
   • 2 ring flagella

5. Gram -

   • Thinner Peptidoglycan
   • Outer Membrane
     • protects bacteria from phagocytosis
       • complements mediated killing and antibiotics
     • made up of
       • lipopolysaccharides
         • Lipid A
           • endotoxin
             • relased withe cell dies or dividing
         • O polysaccharides
           • Cell markers
       • phospholipids
       • lipoproteins
       • porins
         • channels
   • periplasmic space
     • space between outer and phospolipid bilayer
   • 4 ring flagella
     • in basal body

6. Atypical

   • Acid-fast cell walls
     • Mycolic acid
       • bound to PG
   • Mycobacterium
   • Mycoplasmas
     • Lack cell walls
       • Sterols in PM
         • Makes PM strong
   • Archaea
     • Wall less
       • Walls of pseudomurein

7. Damage

   • Lysozyme
     • enzyme in tears, saliva
     • hydrolyez bonds betweens the sugars in peptoglycan
     • Gram +
   • Protoplast
     • wall-less gram + cell
   • Spheroplast
     • Wall-less gram - cell
   • L-Forms
     • Wall-less Cells
       • swell into irregular shapes
     • gram -

8. Plasma Membrane

   • Outer covering
   • Encloses Cytoplasm
   • Phospholipid bilayer and Proteins
   • Eukaryotes
     • Contains carbs and sterols
   • Prokaryotes
     • lacks sterols
   • Selective permeability
     • Active
   • Contains Enzymes for ATP

9. Proteins

   • Periphal Proteins
     • membrane surface (inner or outer)
     • easily removable
   • Intergral Proteins
     • difficult to remove
     • most are transmembrane proteins
   • Glycoproteins
     • proteins with carbs
   • Glycolipids
     • lipids with carbs