Module 8.1: Cell Wall

These flashcards cover key vocabulary related to the structure and function of bacterial cell walls, their clinical significance, and the effects of antibiotics.

N-acetylglucosamine (NAG)

A key component of bacterial cell walls that forms part of the peptidoglycan structure.

N-acetylmuramic acid (NAM)

Another vital component of bacterial cell walls, which, together with NAG, forms the backbone of peptidoglycan.

Tetrapeptide

4 amino acids attatched to NAM that are cross-linked with peptide crossbridge that strengthens the structure of the cell wall

What are the functions of the cell wall?

Shape, resist osmotic pressure, prortect membrane and interior from adverse enviroment changes, anchorage for flaglla, ALL bacteria have a cell wall except Mycoplasma

Clinical function of cell wall?

contributes to ability to cause disease for some species, site of action for some antibiotics, used to differentiate bacteria

Gram Positive Bacteria

Wall outside the plasma membrane, 20-80nm thick (20%-30% dry weight), MANY layers of peptidoglycan, contains teichoic acids= alcohol + phosphate, stains purple on gram stain, mycolic acid in Mycobacterium= thick, waxy liquid

what do Teichoic acids do?

Regulate cations into and out of cell, regulate autolysins that degrade cell wall, antigenic specifically for ID, achors cell wall to plasma membrane

Gram Negative Bacteria have a outer membrane (part of cell wall) that are?

not very permeable to antibiotics because not lipid soluble, contains lipopolysaccarhides (LPS), has true lipid bilayer of phospholipids,

Lipopolysaccharides (LPS)

A component of the outer membrane of Gram-negative bacteria that can provoke strong immune responses.

Gram negative has a thin layer of?

Peptidoglycan (1-31nm) in the periplasmic space between membranes, which is between the two membranes

Gram negative is also?

Heat stable= not destroyed by autoclaving, toxic at high doses (mg/kg), capable of producing fever, blood clots, weakness, shock, and even death due to hemorrhagic shock

Factors that destroy cell wall?

Lysozome = enzyme that breaks the NAM-NAG, found in egg whites and tears, only works on GM +

Penicillin= antibiotic that prevents crosslinking in wall from occurring (synthesis of wall)

Osmotic Pressure

The pressure exerted by the movement of water across the bacterial cell membrane, which the cell wall helps to resist.

Mycoplasma

A genus of bacteria that lacks a cell wall, making them resistant to antibiotics that target cell wall synthesis.