Principle of Micro 2 continued Flashcards
In S. aureus how are NAM and NAG linked
via beta 1-4 linkage
for gram positive in S. aureus, how are the chains (NAM and NAM) linked
link is established between the third amino acid on one NAM with the fourth amino acid on the other
what are the four amino acids in gram positive
L-alanine
D- glutamine
L-lysine
D- alanine
what is the importance of the D-alanine in gram positive
on the NAM that uses the third amino acid for linkage, it releases D-alanine for energy to make the linkage possible
what are the four amino acids in gram negative
L-alanine
D-glutamic acid
meso-diaminopimelic acid
D- alanine
D-alanine also released for energy
what does lysozyme do
breaks the beta 1,4 linkage weakening the cell wall hence causing cell to burst
in gram negative, what is between the peptidogylcan and cell membrane/cytoplasmic membrane
periplasmic gel
important structure in the outer membrane of gram negative
LPS endotoxin
what anchors the LPS
Lipid A
importance of the O polysaccharide
- adhesion at specific sites
- resistance of phagocytosis
- carrier for lipid A
- protection against antibody and complement
- antigenic variation
what happens if there is a small change in sequence in the O polysaccharide
significant change in virulence
significance of Lipid A from human disease perspective
- powerful biological response modifier
- significant contribution to symptoms and pathology
- B cell mitogen
impact of gram positive and gram negative on cellular permeability
gram positive - more permeable
gram negative - less permeable
what does mycoplasma have instead of cell wall
sterols and lipids
