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teichoic acids
Many Gram-positive Bacteria have acidic polysaccharides called teichoic acids embedded in their cell wall
The amino acids present for pseudomurein
in the L-isoform
The term teichoic acids includes ex
includes all wall, membrane or capsular polymers containing polyalcohols residues Includes glycerol phosphate or ribitol phosphate (spp. dependent) and are negatively charged
S-layer consists of typically have what shape
interlocking protein or glycoprotein Typically have hexagonal symmetry
A major function of the LPS is to
keep proteins from diffusing away
Teichoic acids are negatively charged, therefore they are partially responsible for
the negative charge on Gram-positive cell surface No clear known function
petidoglycan sugars have what kind of bond and can be broken down by
β 1,4 glycosidic bond lysozyme
The sugar N-acetylmuramic acid (M) and the amino acid DAP are never found in the cell walls of
Archaea or Eukarya
Others cells may lose the cell wall, known as
L-form/cell wall deficient (CWD)
Examples of Bacteria with no cell wall:
Mycoplasma: like a protoplast, lives in osmotically protected environments; contain sterols for added strength to membrane
The pseudomurein backbone is composed of alternating repeats of types of bond
N-acetylglucosamine (G) and N-acetyltalosaminuronic acid (T) The glycosidic bonds are β(1,3) instead of β(1,4)
LPS has what 3 parts and what are they made up of
O-specific polysaccharides is the outermost component Core polysaccharides is made up of sugars, including the unusual sugar KDO (2-keto-3-deoxy-octanoate) Lipid portion (Lipid A) has fatty acids linked to N-acetylglucosamine (G) through the amine groups; forms the inner most component
S-layer also called and a present
Paracrystalline Surface Layer Most common cell wall in Archaea May also be found in Bacteria
septicemia present when examples
Presence of the LPS in the blood Examples of bacteria that can lead to septicemia include: Salmonella, Shigella and E. coli
glycan tetrapeptide
When the sugars and amino acids are connected in peptidoglycan they make up the this
Endotoxins can produce
fever, a decrease in blood pressure, activation of inflammation and coagulation of blood
Most Gram-positive bacilli have DAP instead of
lysine
Peptidoglycan can be destroyed by certain agents, such as
lysozyme
can hydrophobic antibiotics effect gram negative bacteria
no because they can't get through the outer-O-specific polysaccharides
Archaea are naturally resistant to
penicillin or lysozyme that destroy peptidoglycan
Teichoic acids are
polyalcohols connected by phosphate esters along with sugars and D-alanine
Gram-positive: produces when treated with lysozyme in an isotonic environment
protoplast
Breakdown of cell wall in a dilute solution releases the but
protoplast but it immediately lyses because the cytoplasmic membrane is very weak
Some Archaea contain cell walls constructed of a polysaccharide very similar to peptidoglycan Known as
pseudomurein
Gram-negative: treatment with lysozyme produces a
spheroplast which is similar to protoplast but has residual wall attached Gram-negative bacteria contain the LPS layer which is not weakened by lysozyme
Lipoteichoic acids (LTA) are
teichoic acids covalently linked to membrane lipids
Another unusual feature of the bacterial cell wall is the presence of two amino acids
that have the D-configuration D-alanine and D-glutamic acid
which portion of LPS is toxic to animals
the lipid A portion the toxicity is termed endotoxin
peptidoglycan composed of
two sugar derivatives, N-acetylglucosamine (G) and N-acetylmuramic acid (M) tetrapeptide side chain consisting of L-alanine, D-glutamic acid, either L-lysine (Gram-positive) diaminopimelic acid (DAP; Gram-negative) and D-alanine
Non specific porins are
water filled channels