Bacterial Classification and Structure Flashcards
which bugs have capsule as major virulence factor?
SOME KILLERS HAVE PRETTY NICE CAPSULES
- strep pneumoniae
- kliebsiella pneumoniae
- haemophilus influenzae
- pseudomonas aeruginosa
- neisseria meningitidis
- cryptococcus neoformans
where are pili found
gram negative only
what component is responsible for cell shape and structural rigidity
peptidoglycan
what makes up peptidoglycan
NAG and NAM that are crosslinked by tetrapeptide bridge
describe gram positive cell wall
thick peptidoglycan, highly crosslinked, has lipoteichoic acid and teichoic acids
what do lipoteichoic acids do
anchor cell wall to cell membrane and mediate attachment
what do teichoic acids do
taxonomic markers , antigenic determinant
gram negative cell structure
2 membranes inner and outer, with periplasmic space, has less peptidoglycan with less crosslinkage
describe outer membrane of gram negative cell
gram negative has LPS, there is no active transport or enzymatic activity, there are porins and receptor proteins
what is a main part of LPS?
Lipid A
what is Lipid A?
heat stable endotoxin with a core region and polysaccharide side chain (o antigen) – a pyrogen
what does Lipid A do?
activates macrophages and complement and B cells
induces IFN production
causes tissue necrosis
pyrogen
what does O antigen do
is a major serologic determinant and a virulence factor (if smooth making O antigen, if rough not making O antigen)
what is in the periplasmic space?
- binding proteins
- degradative enzymes
- detoxifying enzymes
- super thin peptidoglycan cell wall
what detoxifying enzymes are in the periplasmic space?
beta lactamases (inhibit penicillin and cephalosporins, carbapenems, monobactams)
describe the inner membrane of (both gram positive and negative)
similar in both, NO STEROLS, osmotically fragile
HAS ENZYMATIC ACTIVITY, acts like osmotic barrier
what type of activity does the cytoplasmic/inner membrane have?
- electron transport
- ox phosphorylation
- synthesis of peptidoglycan
- active transport
- bounds ribosomes
- simple and facilitated diffusion
where do endospores come from
gram positive
what is the purpose of becoming a spore
to survive and be stable not reproduce
what triggers spore formation?
exhaustion of carbon or nitrogen source
what is a big clue that someone has spore infection?
accumulation of large amounts of calcium and dipicolinic acid
structure of endospore
- core with genome, DNA and ribosomes
- spore wall with peptidoglycan
- cortex with new peptidoglycan
- coat
- exosporium loose covering
is there RNA or free AA in endospore core>
no
thickest layer in endospore
cortex - concentric layers give strength
what is the benefit of a spore coat?
disulfide bonds and keratin like protein makes it resistant to chemicals and radiation
what triggers activation of spore germination?
either spontaneous or heat, aging, low pH, or chemical treatments
what occurs when spore germinates?
produces Ca and dipicolinic acid, hydrolysis begins and brings in water, but loses heat resistance
what is crucial for spore germination?
water
which bacteria are spore formers
- clostridium tetani
- clostridium botulinum
- bacillus anthracis
- bacillus cereus
