Infectious Microorganisms Flashcards
What are 3 aspects of the prokaryotic bacteria cell
- unicellular
- lacks membrane bound nucleus or organelles
- binary fission
What does the hypha and stalk help with
movement
What are 3 function of the cytoplasmic membrane
- permeability barrier
- protein anchor
- energy conservation and proton motive force
What is the fundamental unit of peptidoglycan
glycan tetrapeptide (G + M sugar + 4 AA)
What is the conformation of the AA in bacteria and humans
D in bacteria, L in humans
What sugar binds the AA
n-acetylmuramic acid
What is the interbridge in gram positive composed of
5 Gly residues
What stabilizes the peptidoglycan
M-M peptide bonds y axis and glycosidic bonds x axis
What does teixobactin target
gram positive bacteria with teichoic acids
What is in the cell wall of gram positive bacteria
thick peptidoglycan layer with periplasmic space
many have negatively charged teichoic acids that attract cations
What is in the cell wall of gram negative bacteria
thin peptidoglycan layer with an additional outer lipopolysaccharide membrane (LPS)
What is LPS and what does it contain
lipid A (endotoxin), core polysaccharide, O-polysaccharide
What are porins
channels for movement of hydrophilic low weight substances
What allows us to identify the gram negative species of bacteria
O-polysaccharide
What is similar and different of capsule and slime layers
Both assist in attachment to surfaces, prevent drying, and evasion of immune system
Capsule organized, while slime disorganized
What is similar and different between fimbriae and pili
Both filamentous and allow to stick to surfaces
Pili usually longer and can allow for genetic exchange (conjugation)
What does type IV pili do
twitching motility
What is colour of positive and negative bacteria undergoing the gram stain and why
Gram positive thick layer does not take up second colour - blue/violet
Gram negative thin takes up second counterstain - red
Cocci is most common in negative or positive
Bacilli is most common in negative or positive
positive
negative
What are the steps to the gram stain
- Suspend bacteria on slide
- Crystal violet 1 minute then wash
- Iodine 1 minute then wash
- 95% alcohol 10 sec then wash
- Safranin counterstain 30 sec
