Lecture 4

Question 1

What are the 2 types of bacterial cell walls?

Answer 1

Gram positive and Gram Negative

Question 2

What is a Gram positive cell wall made of?

Answer 2

A thick layer of peptidoglycan surrounds the phospholipid bilayer. The PG sections are linked together with teichoic acid. The PG attaches to the cell membrane with lipoteichoic acid and a lipid segment

Question 3

How does PG stay together?

Answer 3

PG has strands of NAG and NAM that will attach to other strands of NAG and NAM with a peptide crosslink

Question 4

What is a Gram Negative Cell Wall made of?

Answer 4

A thin layer of PG surrounds the cell membrane, it is attached and held together by teichoic acid and lipoteichoic acid like the PG layer in Gram Positive. The PG layer is surrounded by an outer membrane that has an inner leaflet made of phospholipids and an outer leaflet made of LPS, called the LPS membrane

Question 5

What is LPS?

Answer 5

Lipopolysaccharides which have a sugar head instead of a phosphate head. The LPS membrane is not a major permeability barrier

Question 6

What are teichoic acid and lipoteichoic acid? What do they do?

Answer 6

T acid connects layers of PG and L acid connects the whole thing to the cell membrane

Question 7

What is a flagellum? How does it work?

Answer 7

A tail on bacteria that helps it move in a corkscrew motion. The “tail” is a filament made of flagellin (protein with 4°) and a basal apparatus anchors the whole thing in the cell wall and is what turns the whole thing

Question 8

How does the Basal Apparatus work?

Answer 8

It is made up of complex gears that will turn the whole thing in a corkscrew motion, the gears are moved by an H+ gradient as H+ moves into the cell