Bacterial Cell Walls

Flashcards about Bacterial Cell Walls

Cell Wall (Sacculus)

Confers shape and rigidity to the cell and protects the cell membrane.

Mycoplasmas

Prokaryotes that have a cell membrane with no cell wall.

Glycan

A disaccharide unit that has an attached peptide of four to six amino acids.

Peptidoglycan Structure (Murein)

Meshlike polymer of identical subunits forming long strands, consisting of two alternating sugars: N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM), and amino acids.

Peptidoglycan

Unique to bacteria, and the enzymes responsible for its biosynthesis make excellent targets for antibiotics.

Penicillin

Targets transpeptidase, the enzyme that cross-links the amino acids in peptidoglycan.

Firmicutes

Gram-positive bacteria that have multiple layers of peptidoglycan threaded by teichoic acids.

Teichoic Acid

Glycerol or ribitol phosphodiester chains that are negatively charged cross-threads that help retain basic dyes.

Proteobacteria

Gram-negative bacteria that have thin layers of peptidoglycan and an outer membrane.

Lipopolysaccharides (LPS)

In outer membrane act as endotoxin; when released, overstimulates immune cells, causing a cytokine storm.

Porins

Allow the passage of nutrients and are also the site of antibiotic entry in the outer membrane of Gram-negative bacteria.

Genus Mycobacterium

Contain mycolic acids (fatty acids) linked to arabinogalactan (a polysaccharide) linked to peptidoglycan.

Genus Mycoplasma

Lack cell walls and are pleomorphic. Cannot synthesize peptidoglycan. Sterols may stabilize plasma membrane; smallest bacteria capable of self-reproduction.

Mycoplasma gallisepticum

Chronic respiratory disease in chickens.

Mycoplasma pneumoniae

Primary atypical pneumonia in humans, also known as 'Walking pneumonia'.