Jac Flashcards
T/F: Bacterial mrNA is capped and polyadenylated
mRNA doesn’t have 5’ cap structure, 3’’ end not polyadenylated
T/F:Bacterial capsules are always conserved between species of same genus
FALSE: E.g. Neisseria
Capsules of N. menngitidis vary significantly - 13 serogroups
type B most common capsule type
T/F: all capsules are made of polysaccharide
FALSE: Can be amino acid
PAP pili
Comprise many subunits
UTIs caused by uropathogenic E.coli may ascent to kidney
because bacteria express Pap Pili which recognise galactose disaccharide on kidney endothelium
P pili mediate binding to Gala(1-4) Gal disaccharides present on kidney epithelium via PapG adhesin
Cell Wall
Structural support
Protects from toxic substances
Contribute to pathogenicity
Site of action of some antibiotics
GP cell wall
E.g. bacillus, staphylococcus, streptococcus
Teichoic acid: ribitol + glycerol + phosphate
Lipoteichoic acid: attached to lipids in membrane
GN cell wall
E.g. E.coli and salmonella
Peptidoglycan = 1nm
LPS
LPS
Endotoxin 3 parts: 1. Lipid A (toxic 2. Core polysaccharide 3. O-specific polysaccharide side chain Recognised by TLR4
Capsule
Composed of glycocalyx
Mostly polysaccharide, can be polypeptide
Capsule: glycocalyx composed of organised repeating units firmly attached to cell surface
Slime layer: loosely water-soluble glycocalyx
Protect cell from dessication
Capsule functions
Prevent phagocytosis Prevent opsonization Promote adhesion Promote biofilm formation Often poor antigens Typical feature of blood-borne pathogens
Flagella
3 parts: long thin filament, hook, basal body
Run - movement in single direction
Tumble - random changes in direction
Recognised by TLR5
Fimbrae/pili
Nonmotile
Adherence - colonization
Type 4 pili
polar
form bundles
twitching motility
EPEC
Intimin: afimbrial adhesin
Tir: translocated intimin receptor - secreted by T3SS and deposited in membrane
Tir binds intimin and binds cytoskeletal proteins(intracellular)
