microbiology Flashcards
Gram positive meaning
have a cell membrane AND a peptidoglycan layer
peptidoglycan layer aka and components
aka murein
cotains teichoic acids and lipoteichoic acids and proteins
Murein cell wall force
HYDROPHILLIC so hydrophilic components can get through but NOT hydrophobic
Teichoic acid role in pathogenesis
by promoting adherence to host tissues
Colour of gram positive
PURPLE
gram negative meaning
have a cell membrane AND thin murein layer AND lipopolysaccharide outer membrane
Outer membrane made of what on gram negative bacteria
lipopolysaccharides
1. Lipid A
2. Core polysaccharide
3. O antigen
WHat is and purpose of lipid A in lipopolysaccharide outer cell membrane (|gram -ive)
embeds the LPS in outer leaflet of membrane
IS AN ENDOTOXIN –> causes fevers and shock
What is the purpose of O antigen in gram -ive LPS of outer membrane
hydrophilic carbohydrate chain that excludes hydrophobic compounds
Colour of gram negative
red/pink
what are exotoxins and what are subcomponenets called
- toxins secreted by the bacteria
- made of A and B subunits
- toxins bind to receptor and then endocytosed by host cells
- A (active subunit) then released into cytoplasm –> effects cell
What are type III cytotoxins
- toxins injected into host cell by a secretory injection system (type III secretory apparatus)
- then modulate intracellular behaviour
- found in salmonella / shigella / cholorea
other types of exotoxin
- PPR toxins –> cause cytokine release
- pore forming toxins
- superantigens (bind to TCR and MHC to induce formation of toxic compounds
What are botulinum and tetanus toxins and whats diff about them
NEUROTOXINS
- tetanus = muscle contraction = spastic paralysis
- botulinum = block muscle contraction = flaccid paralysis
Endotoxins
part of LPS outer membrane in gram negative bacteria (lipid A)
- LPS recognised by pattern recognition receptor –> causes cytokine production = BAD
Examples of effects of endotoxins in small amounts
