Lecture 2- Bacterial motility and adhesion Flashcards
Is gram positive homogenous or heterogenous?
homogeneous
Where do you find teichoic acid?
Only find it in gram positive
Under scanning EM what do the surfaces look like of gram positive and negative?
Gram positive- smooth surface (homogenous)
Gram negative- ruffled surface, because heterogenous
What is lipid A?
Lipid A is the endotoxin. The endotoxin causes the symptoms of the disease.
How do the number of fatty acyl chains change the properties?
If you have fewer fatty acyl chains, not as bad an effect. (more chains, worse effect)
What are fimbrae?
short, thin flagella
What do fimbrae do and how?
Allow bacteria to adhere to cells.
At the tip there’s a single protein that attaches to mannose receptors on the host cell.
How do fimbrae grow?
They have hollow centres. The new proteins go up through the hole and attach at the top. (rather than growing from bottom)
The last stage of peptidoglycan biosynthesis is the formation of the peptidoglycan bridge. What makes this?
Transpeptidase / carboxypeptidase
What is only found in gram negative?
What is only found in gram positive?
Only get DAP in gram negative.
Only get L-lysine in gram positive.
In flagella what does the hook do?
Hook- transfers the rotary motion to the filament
What does the mot protein do?
Mot- motor proteins surround rotary base. Conduct electric current from the periplasm into the cytoplasm. This powers the rotation.
What are 5 properties of flagella?
- Helical and rigid
- 20nm diameter
- consists of protein subunits-flagellin
- Anchored in cytosolic membrane
- Have a biological rotary motor at the base
What’s LPS?
LPS- lipopolysaccharide. Holds the whole cell together. Important
What are the parts of the LPS?
A lipid A embedded in the membrane.
Then a core polysaccharide.
Then an O-specific polysaccharide side chain. (projecting away from cell surface)
What are the types of flagella?
Can be polar or petrichous
Polar- flagella on one side or both sides
Petrichous- spread around it
How do flagella move in eukaryotes and prokaryotes?
Eucharyotic go side to side.
Bacterial spin
How much cross-linking is there in gram negative and positive?
Gram negative- one layer thick. there’s low cross linking of NAM to NAM
Game positive- more cross linking
How does penicillin work?
Penicillin inhibits cross-linking of tetrapeptide cross linkages.
How does the peptidoglycan structure differ between gram negative and gram positive?
They have different side chains
Which has a peptide cross bridge and which just as a direct link?
(gram pos. and neg.)
Gram pos- have 5 glycine (peptide cross bridge) residues interbridging the side chains.
Gram neg- doesn’t!
What makes up the “ribbon-like” structure of peptidoglycan?
A carbohydrate backbone with amino acids joining the chains
What are the peptidoglycan polymers made of?
Made of 2 sugars-
- N-acetyl glycosamine (NAG)
- N-acetyl muramic acid (NAM)
How are the peptide chains joined together?
Amino acids between NAMs
