gram negative and gram positive cell walls Flashcards
s layer
single layers of thousands of copies of a single protein linked together like tiny chain link fences
only produced when bacteria are in a hostile environment
glycocalyx
coating of repeating polysaccharide or glycoprotein units
slime layer
capsule
slime layer
in glycocalyx
loose protects against loss of water and nutrients
capsule
in glycocalyx
more tightly bound, denser, and thicker
produce a sticky (mucoid) character to colonies on agar
specialized functions of glycocalyx
capsules:
formed by many pathogenic bacteria
have greaer disease-causing bacteria
protect against host white blood cells called phagocytes
specialized functions of glycocalyx
biofilms:
plaque on teeth protects bacteria from becoming dislodged
responsible for persistent colonization of plastic catheters, IUDs, metal pacemakers, & other implanted medical devices
cell envelope
cell wall
cytoplasmic membrane
outer membrane (in gram negative bacteria)
cell wall
helps determine the shape of a bacterium
provides strong structural support to keep the bacterium from bursting or collapsing because of changes in osmotic pressure
gains its relative rigidity from peptidoglycan
peptidoglycan
compound composed of repeating framework of long glycan sugar chains (sugar) chains cross linked by short peptide (protein filaments)
N-acetylglucosamine (NAG)
N-acetylmuramic acid
(NAM)
provides a strong but flexible support framework
gram positive cell wall
thick, homogenous sheet of peptidoglycan
aside, stacked on top of each other
protects and gives cell shape
contains teichoic acid and lipoteichoic acid
function in cell wall maintenance and enlargement
contribute to the acidic charge on cell surface
gram negative cell wall
single thin sheet of peptidoglycan
thinness gives these cells mosre susceptibility to lysis
outermembrane
thin layer
plasma membrane
gram negative outer membrane contains
lipopolysaccharide
porin proteins
lipopolysaccharide
signaling molecules and receptors
endotoxin
porin proteins
special membrane channels that only the outer membrane allows certain chemicals to penetrate
