MCB Chapter 3 (Cell wall structure) PDF

Preview

Summary

cell wall structure review...

Description

MCB Chapter 3 (peptidoglycan structure) 1. What is peptidoglycan made of?

Sugars and peptides

2. Which 2 sugars are used in peptidoglycan?

N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM)

3. What type of bond is between the two sugars?

β(1-4) glycosidic bonds

4. Which sugar are the peptides attached to?

NAM

5. In order what peptides are used in gram negative bacteria

L-Alanine, D-Glucose, DAP, and D-Alanine

6. Do gram negative or positive have a peptide interbridge made of Gly connecting the two peptide tails?

Gram positive

7. In order what peptides are used in gram positive bacteria

L-Alanine, D-GluNH2, L-Lysine, and D-Alanine

8. Glycosidic bonds confer strength in the

X direction

9. Peptide bonds confer strength in the

Y direction

10. What two peptides are different in gram negative and gram positive bacteria

DAP in gram neg, L-Lys in gram positive

11. D-alanine connects with what in gram negative bacteria to form a peptide bond?

DAP

12. D-alanine connects with what in gram positive bacteria to form a peptide bond?

L-Lys through a Gly peptide interbridge

13. Lysozyme

breaks β(1-4) glycosidic bonds

14. What is an example of a bacteria that would have DAP in the 3rd position

E. coli

15. What is an example of a bacteria that

Staphylococcus aureus

would have L-Lys in the 3rd position

16. When forming the peptide cross-bridge what happens

Terminal D-Alanine is removed

17. Vancomycin and penicillin do what

Inhibit the removal of the terminal D-Alanine therefore inhibiting the making of the cell wall

18. What gives gram positive bacteria their negative charge

Teichoic acid

19. Teichoic acids are

polymers of glycerol or ribitol joined by phosphate groups

20. Exoenzymes

serve to degrade polymers such as proteins and polysaccharides that would otherwise be too large for transport across the plasma membrane

21. do gram positives have a periplasmic space?

Yes between the plasma membrane and the peptidoglycan

22. what give gram negatives their negative

lipopolysaccharide (LPS)

charge?

23. do gram negative have teichoic acid?

no

24. what is a lipoteichoic acid

Teichoic acid that goes thought e peptidoglycan all the way to the cell membrane

25. Brauns lipoproteins

Links the outer membrane with the thin peptidoglycan

26. Porin

Less specific then a permease and allows transport across the outer membrane, they are filled with water and allow the passage of nutrients and hydrophilic molecules

27. The outer membrane of the bacterial cell wall is

A phospholipid bilayer that resides on the outside of the thin layer of peptidoglycan that only gram negatives have

28. Where is the peptidoglycan found in gram negative bacteria?

In the periplasmic space between the inner and outer plasma membranes

29. What are the three parts of

lipid A

lipopolysaccharides (LPS)?

core polysaccharide (KDO (2-keto-3-deoxyoctanoate)) O side chain (O antigen)

30. Regarding to the LPS each species and strain has its own

O-specific polysaccharide

31. Lysozyme

An enzyme that breaks the cell wall

32. Protoplasts

Cell that lost its cell wall but was originally a gram positive, it now only has the cell membrane and plasma

33. Spheroplasts

Cell that lost its cell wall but was originally a gram negative, it now only has cell membrane, pieces of peptidoglycan and the outermembrane

34. What are the 5 important functions of LPS

1) It contributes to the negative charge on the bacterial surface 2) It helps stabilize outer membrane structure because lipid A is a major constituent of the exterior leaflet of the outer membrane 3) It helps create a permeability barrier 4) helps protect pathogenic bacteria from host defenses 5) lipid A portion of LPS can act as a toxin and is called endotoxin...