Bacteria and Archaea Cell Structures II

Question 1

Gram-negative bacteria have (thick or thin) cell walls?

Answer 1

thin

Question 2

Gram staining reveals the differences in the thickness of which layer in different bacteria?

Answer 2

Peptidoglycan layer

Question 3

KNOW how to draw gram-negative cell envelope

Answer 3

Do it
Outer membrane
Periplasmic space
Peptidoglycan 
Plasma Membrane

Question 4

Gram (+ or -) has a greater periplasmic space?

Answer 4

negative

Question 5

KNOW the Murein subunit

Answer 5

NAG-NAM-L-Ala-D-Glu-DAP-D-Ala-D-Ala (unlinked)

Question 6

What are the three main components of Gram-positive cell envelopes?

Answer 6

1. Peptidoglycan
2. Periplasmic space
3. Plasma membrane

Question 7

Peptidoglycan (Murein) are what?

Answer 7

Mesh-like polymer composed of identical subunits
(NAG-NAM)
Cross-linked

Question 8

L amino acids are considered (standard or non-standard)?
D amino acids are considered (standard or non-standard)?
(L or D) amino acids help protect against degradation by proteases?

Answer 8

Standard
Non-standard
D

Question 9

KNOW how to draw Gram-negative cross-link

Answer 9

Do it
Last D-Ala is removed
D-Ala to DAP

Question 10

Cross-link in Gram-positive has what kind of bridge?

Answer 10

peptide interbridge

Question 11

KNOW how to label a Gram-negative diagram

Answer 11

Do it (p. 7)
Contains porins to allow movement of molecules

Question 12

Lipopolysaccharides (LPSs) are present instead of what compound in the outer leaflet?

Answer 12

phospholipids

Question 13

LPSs contributes to the (+ or -) charge on the cell surface?
They help stabilize (outer or inner) membrane structure?
Act as a ___ (cause septic shock)

Answer 13

(-)
Outer
Endotoxin

Question 14

Polymyxin B is an antibiotic that does what?

Answer 14

Antibiotic that targets the LPS

- binds to it and causes leakage in the cell

Question 15

What is the significance of LPS?

Answer 15

Gram negative contains this in their outer membrane, which limits what compounds can enter and reach the peptidoglycan

Question 16

What is the name of an important antibiotic that targets the cell wall?

Answer 16

Penicillin

- causes lysis due to swelling (in hypotonic solution)

Question 17

LPS are found in gram (+ or -)?

Answer 17

negative (contribute to negative charge)