Lecture 1 Flashcards
interactions/forces involved in nonspecific adherence
- hydrophobic interactions
- electrostatic attractions
- atomic and molecular vibrations resulting from fluctuating dipoles of similar frequencies
- Brownian movement (random interactions)
- recruitment and trapping by biofilm polymers interacting with the bacterial glycocalyx (capsule)
nonspecific adherence is ____ and is called ____
reversible; docking
specific adherence is ____ and is called _____
irreversible; anchoring
adhesins are often found on ____ but can be found in capsules or cell surface
fimbrae (aka pili)
why does streptococcus mutans (cause of caries) bind to tooth pellicle?
the adhesin is glucosyl transferase which binds to a salivary protein that is involved in pellicle formation
how do bacteria take up nutrients?
- carrier-mediated diffusion (facilitated)
- phosphorylation-linked transport (group translocation)
- active transport (energy dependent)
____ can facilitate invasion such as _____
secreted enzymes; hyaluronidase, steptokinase, specific proteins that induce endocytosis/phagocytosis
2 different mechanisms for spread
- lateral propagation to contiguous tissues (multiply then spread)
- dissemination to distant sites (spread then multiply)
endotoxins are a component of the bacteria ____, released when the cell disintegrates; endotoxin term usually reserved for _____
cell wall; lipopolysaccharides
exotoxins are ____ substances secreted into _____
soluble; host tissues
what makes a microbe a pathogen?
- ability to adhere to host
- ability to colonize the host
- ability to replicate within a given niche
- ability to cause damage (invasion, production of toxin, activation of the immune system)
bacterial responses to oxygen
- strict aerobes- must have oxygen to grow
- obligate anaerobes- cannot grow in presence of oxygen
- facultative anaerobes- can grow with or without oxygen (most medically important)
microbes that can grow with limited nutrients
oligotrophs
microbes that require some oxygen, but lower levels of oxygen
microaerophiles
grow well in mild temperatures (15-45 C)
mesophiles
difference in envelope structure of Gram + and gram – bacteria
Gram + has thick layer of murein (peptidoglycan) on top which helps cell to maintain shape
Gram - has second lipid bilayer on top
murein has a ____ structure to help with rigidity
cross-linked
composition of ____ is slightly different for Gram+/- bacteria; Gram negative has ____ terminal
DAP (diaminopimelic acid) –D-alanine
between cell membrane and cell wall (murein) is the ____
periplasmic space
gram negative has ____ surface structure and gram positive has ____ surface structure
LPS; teichoic acid
LPS is made up of ____, ____ and ____
lipid A; core polysaccharide; repeating O-antigen subunits
____ is the main reason for the different antigenic specificities among gram negative bacteria
O-antigen
structures within bacteria are important bc they are considered ____
pathogen associated molecular patterns (PAMPs)
cells of the immune system can recognize PAMPs using _____
pattern recognition receptors (PRRs)
_____ recognizes LPS
toll-like receptor 4
_____ recognizes peptidoglycan
toll-like receptor 2
____ together recognize teichoic acids
toll-receptors 2 and 6
involved in the attachment of bacteria to cells and other surfaces
pili (fimbriae)
when movement of flagella is directed it is referred to as ____
taxis
a substance that surrounds a cell outside the cell wall or lipid membrane
glycocalyx
glycocalyx that is well organized and firmly attached is a ____
capsule
capsules are usually made of _____ but can include ____ and _____
polysaccharides; monosaccharides; glycoproteins
glycocalyx that is not well organized or firmly attached is called a _____
slime layer
why would capsules be beneficial to pathogens?
for some bacteria, encapsulation is a necessary virulence factor
_____ can recognize flagella
toll-like receptor 5
if a microbe is gram negative, you know it has ____ (designated by ____ in the name)
LPS; O-antigen
if a microbe is motile, you know it has ____, designated by the ____ in the name
a flagellum (or multiple flagella); H-antigen
____ refer to capsules
K-antigens
