Exam 1 - (2) Surface Structures Flashcards
Gram + bacteria express ______ on their outermost surface. Gram - express ______.
- Teichoic acid
- LPS
Two types of teichoic acid are:
- Glycerol Teichoic acid
- Ribotol Teichoic acid
_______ are embedded deeper in the the peptidoglycan layer of Gram + bacteria than the similar teichoic acids.
-Lipoteichoic acids
Describe the structure of Lipopolysaccharide (LPS):
-Lipid A attached to a core polysaccharide attached to am O-antigen
What is a Lipid A (within LPS)?
fatty acids attached to a phosphorylated disaccharide
Describe a polysaccharide core (within LPS)?
It is similar between Gm- bacteria, but with unique sugars.
Describe the O-antigen within LPS’s structure:
What is it the main reason for?
- highly variable repeating sugar subunits.
- antigenic specificity among Gm- bacteria
What type of toxin is LPS?
Endotoxin
In regards to immunology, what is important about the pathogenic surface structures?
-They are considered pathogen assc. molecular patterns (PAMPS)
What do cells of the immune system use to recognize PAMPs?
pattern recognition receptors (PRRs)
Name 3 “Toll-like” PRRs and what they recognize:
- Toll-like receptor 4 -> LPS
- Toll-like receptor 2 -> peptidoglycan
- Toll-like receptor 2 and 6 together -> teichoic acids
What are pili/fimbriae involved in?
attachment of the bacteria to cells and other surfaces
What specialized proteins can be found on the tips of fimbriae and what are they developed for?
- Adhesins
- adherence
What are sex pili for? ;)
conjugation/transference of genetic material between adjacent bacteria
name there types of fimbriae/flagella arrangements:
1-Monotrichous (one squiggly, like a sperm)
2-Lophotrichous (a few squigglys)
3-Peritrichous (covered with squigglys)
The base for a flagella/fimbriae is _____ in all layers of the bacterial mebrane/cell wall via specific ______ and ______.
- embedded
- rings (superficial to deep L, P, MS, C)
- proteins
Flagella play a role in bacterial motility and can rotate clockwise and counter clockwise to achieve this.
cool
Movement by a flagellum can be ______ or ______.
- random
- directed
Directed flagellar movement is called______. It can be towards something good or away from something bad.
Taxis
Name 4 types of taxis:
1-Chemotaxis (toward chemoattractant or away from chemorepellant.
2-Aerotaxis
3-Osmotaxis
4-Thermotaxis
What is a Glycocalyx?
a substance that surrounds the cell
What type of glycocalyx is referred to as a capsule?
one that is well organized and firmly attached
What is the chemical makeup of a capsule?
polysaccharides typically, but sometimes monosaccharides and glycoproteins.
What is a glycocalyx that is not well organized or firmly attached?
a slime layer
Why are capsules beneficial to pathogens?
for some bacteria, encapsulation is a necessary virulence factor. (S. pneumoniae only causes pneumonia with a capsule).
Can the immune system recognize capsules?
YES!!!!!
Toll-like receptor 5 recognizes _________, and sometime the _______ can be recognized by the immune system.
- flagella
- capsular polysaccharide
What happens when the immune system recognizes a microbe?
-macrophagy, release of leukocytes, learning by T-cells, a bunch of stuff.
A notorious hamburger pathogen is given the serological designation: E. coli O157:H7. What can this tell us?
- O157: the 157th type of O antigen that was characterized (gram negative b/c LPS)
- H7: the 7th type of H antigen that was characterized (present in flagella, so it is motile)
- it doesn’t have a capsule (K antigens refer to capsules)
