Bacterial Structure

Question 1

What acts as a permeability barrier to bacterial and what structure found in gram negative bacteria affects this permeability? (2 items)

Answer 1

The outer membrane; porins

Question 2

What outer structure molecule is unique to gram positive bacteria?

Answer 2

Lipoteichoic (teichoic acid)

Question 3

What are the Pathogen Associate Recognition Patterns for bacteria? (2 items)

Answer 3

–
Gram negative bacteria -
Lipopolysaccharide (LPS) 
–
Gram positive bacteria -
Lipoteichoic Acid

Question 4

What makes the PAMPs good structures to be recognized by the TLRs on defense cells?

Answer 4

PAMPs
are essential for the survival of bacteria (pathogens) and
with conserved structure

Question 5

PAMP recognition links what two aspects of the immune system

Answer 5

Innate immunity to adaptive immunity

Question 6

What is the size of the porins in what type of bacteria? (2 items)

Answer 6

600kD; GRAM NEGATIVE bacteria

Question 7

What are the effects/functions of LPS? (2 items)

Answer 7

Stimulate innate immunity (effect); functions in cell growth `

Question 8

What is the common endotoxin of gram negative bacteria? (Hint: It frequently is considered the endotoxin that induced fever)

Answer 8

Lipid A

Question 9

What are the three components of the PAMP (within the outer cell envelope) of gram negative bacteria? (3 items)

Answer 9

1. ) O-antigen (variable)
2. ) Polysaccharide core
3. ) Lipid A

Question 10

Is peptidoglycan in gram negative bacteria used as a barrier?

Answer 10

No. It is not an effective barrier.

Question 11

At what site in peptidoglycan does the lysozyme cleavage operate?

Answer 11

Beta 1,4 linkage

Question 12

What two residues does the beta 1,4 linkage in peptidoglycan connect?

Answer 12

NAG (N-aminoglucosamine) and NAM (n-Acetylmuranic acid)

Question 13

What is the 4 residue structure (in order) of the side chain in peptidoglycan and which of the following two does it bind to (NAG or NAM?) (5 items)

Answer 13

Side Chain

1. ) L-Ala
2. ) D-Glu
3. ) L-Lys
4. ) D-Ala

The first residue of the side chain binds to the NAM.

Question 14

What is the linkage between two side chains in peptidoglycan?

Answer 14

L-Lys (of the first chain) to D-Ala (of the second chain)

(Note: there can be an interbridge between these two residues for length. E.g. 5-glycine interbridge between tetrapeptides in the case of Staphylococcus aureus)

Question 15

What type of bacteria (+ vs. - gram) is crosslinking of L-lysine to D-alanine in peptidoglycan most common?

Answer 15

gram positive bacteria