2-3: Bacterial Cell Walls Flashcards
What is the primary function of the cell wall
Prevent cell from bursting due to osmotic pressures (solutes in cell)
Size of cell wall in gram-negative bacteria
Thin
What is the cell wall comprised of
Peptidoglycan
Structure of peptidoglycan
Chains of glycans linked by peptide bonds
What is the peptidoglycan sugar backbone made of
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
alternating
What kind of linkage connected NAM and NAG
B(1-4) linkages
What kind of isomer makes up peptides
D-isomer of aa
Peptide bonds form between what positions
Position three (DAP) and position four (D-alanine)
How many peptidoglycan layers do gram negative bacteria have
~1-3 (2-7nm thick)
How many peptidoglycan layers do gram positive bacteria have
15+ (20-35nm thick)
Peptide crosslinks present in gram positive cells to help connect different peptidoglycan layers
Interbridges
What are teichoic acids attached to
Peptidoglycan
OR lipoteichoic acids are attached to CM
What is the role of teichoic acids
Provide cell strength, trap divalent metal ions, barrier and attachment
What is the function of wall-associated proteins, how do they associate
Many functions, cell adhesion
Associate covalently or non-covalently
How are cell walls dynamic?
Not stagnant. Constantly being synthesized, degraded, remodeled
