Chapter 3.6 Cell Wall

How does the action of penicillin differ from that of lysosyme?

Penicillin prevents the cross-linking of adjacent glycan chains whereas lysosyme breaks the bonds of alternating glycan chains

Mycotplasma

pneumonia, no cell wall, has sterols in their cytoplasmic membrane, makes it strong

Gram-positive cell walls

THICK layers of peptidoglycan, 200+layers, permeable to sugars, amino acids, and other substances, teichoic acids

Gram-negative cell walls

THIN layers of peptidoglycan made up of only 1-2 sheets of interconnected glycan chains

What is attached to the NAM molecule?

Tetrapeptide (string of 4 amino acids), forms a chain link fence between adjacent glycan chains

Structure of Peptidoglycan

alternating series of NAM and NAG (related to glucose, forms a glycan chain which is a linear polymer that is the backbone of peptidoglycan molecule

Endotoxin

body response to gram-negative LPS, large amounts can be deadly

Lysozyme

enzyme found in tears, saliva, and many other body fluids - BREAKS the bonds that link the alternating subunits of the glycan chain which destroys the structural integrity of the peptidoglycan molecule

The NAG and NAM sugars are the

glycan

Penicillin

group of antibiotics that interfere with peptidoglycan synthesis, PREVENTS the cross-linking of adjacent glycan chains, effective in Gram-positive bacteria b/c Gram- neg prevents the medication to reach the peptidoglycan layer

Teichoic Acids

in the thick layer of peptidoglycan, unique molecules that stabilize the layers, negatively charged chains of a common subunit to which sugars are attached,

Gram-negative bacteria are less sensitive to meds b/c

it exudes compounds that could damage the cell

Peptidoglycan

macromolecule that provides strength to the cell wall; it is found only in bacteria

Lipopolysaccharide (LPS)

outside layer of Gram negative wall

The amino acid crosslinks are the

peptide

The Outer Membrane

phosolipid bilayer, except the outer layer is lipopolysaccharide, joined to peptidoglycan by lipoproteins

Periplasm

region between the cytoplasmic membrane and the outer membrane, all exported proteins accumulate here that are used in a variety of cellular activity such as nutrient degradation

What is the significance of Lipid A

responsible for endotoxin, too much of this can be deadly, this is the anchor of the lipid bilayer

Porins

small molecules and ions can pass through specialized channel-forming proteins that span the outer membrane

Prokaryotic Cell Wall

strong, rigid that prevents the cell from bursting

What connects the glycan chains in peptidoglycan?

tetrapeptide (string of 4 amino acids)

Lipid A

the anchor of lipopolysaccharide (LPS) in the lipid bilayer, this is the portion the body recognizes as the sign of invading Gram-negative bacteria (endotoxin)

O antigen

the end opposite Lipid A, made up of sugar molecules, the variation of these molecules are used to identify certain strains