Lecture 2- Bacterial motility and adhesion

Question 1

Is gram positive homogenous or heterogenous?

Answer 1

homogeneous

Question 2

Where do you find teichoic acid?

Answer 2

Only find it in gram positive

Question 3

Under scanning EM what do the surfaces look like of gram positive and negative?

Answer 3

Gram positive- smooth surface (homogenous)

Gram negative- ruffled surface, because heterogenous

Question 4

What is lipid A?

Answer 4

Lipid A is the endotoxin. The endotoxin causes the symptoms of the disease.

Question 5

How do the number of fatty acyl chains change the properties?

Answer 5

If you have fewer fatty acyl chains, not as bad an effect. (more chains, worse effect)

Question 6

What are fimbrae?

Answer 6

short, thin flagella

Question 7

What do fimbrae do and how?

Answer 7

Allow bacteria to adhere to cells.

At the tip there’s a single protein that attaches to mannose receptors on the host cell.

Question 8

How do fimbrae grow?

Answer 8

They have hollow centres. The new proteins go up through the hole and attach at the top. (rather than growing from bottom)

Question 9

The last stage of peptidoglycan biosynthesis is the formation of the peptidoglycan bridge. What makes this?

Answer 9

Transpeptidase / carboxypeptidase

Question 10

What is only found in gram negative?

What is only found in gram positive?

Answer 10

Only get DAP in gram negative.

Only get L-lysine in gram positive.

Question 11

In flagella what does the hook do?

Answer 11

Hook- transfers the rotary motion to the filament

Question 12

What does the mot protein do?

Answer 12

Mot- motor proteins surround rotary base. Conduct electric current from the periplasm into the cytoplasm. This powers the rotation.

Question 13

What are 5 properties of flagella?

Answer 13

1. Helical and rigid
2. 20nm diameter
3. consists of protein subunits-flagellin
4. Anchored in cytosolic membrane
5. Have a biological rotary motor at the base

Question 14

What’s LPS?

Answer 14

LPS- lipopolysaccharide. Holds the whole cell together. Important

Question 15

What are the parts of the LPS?

Answer 15

A lipid A embedded in the membrane.

Then a core polysaccharide.

Then an O-specific polysaccharide side chain. (projecting away from cell surface)

Question 16

What are the types of flagella?

Answer 16

Can be polar or petrichous

Polar- flagella on one side or both sides

Petrichous- spread around it

Question 17

How do flagella move in eukaryotes and prokaryotes?

Answer 17

Eucharyotic go side to side.

Bacterial spin

Question 18

How much cross-linking is there in gram negative and positive?

Answer 18

Gram negative- one layer thick. there’s low cross linking of NAM to NAM

Game positive- more cross linking

Question 19

How does penicillin work?

Answer 19

Penicillin inhibits cross-linking of tetrapeptide cross linkages.

Question 20

How does the peptidoglycan structure differ between gram negative and gram positive?

Answer 20

They have different side chains

Question 21

Which has a peptide cross bridge and which just as a direct link?

(gram pos. and neg.)

Answer 21

Gram pos- have 5 glycine (peptide cross bridge) residues interbridging the side chains.

Gram neg- doesn’t!

Question 22

What makes up the “ribbon-like” structure of peptidoglycan?

Answer 22

A carbohydrate backbone with amino acids joining the chains

Question 23

What are the peptidoglycan polymers made of?

Answer 23

Made of 2 sugars-

1. N-acetyl glycosamine (NAG)
2. N-acetyl muramic acid (NAM)

Question 24

How are the peptide chains joined together?

Answer 24

Amino acids between NAMs