Structure/Function of Bacteria: Cell Wall

MGI 301

peptidoglycan

polymer that surrounds the cell and makes up part of bacterial cell walls, parallel strands of N-acetylglucosamine and N-acetylmauramic acid connected by peptide bonds

lipid A

component of lipopolysaccharide, composed of fatty acids and is anchored to the outer membrane, toxic

core polysaccharide

connect lipid A and O-specific polysaccharide in lipopolysaccharide, composed of various 6-carbon sugars and phosphates

porin

trimeric tube proteins that span the outer membrane bilayer and assist in nutrient transport

semi-rigid

characteristic of a cell wall by being stiff but not inflexible

glycosidic bond

covalent chemical bond that links carbohydrates/sugar molecules together

differential stains

the use of multiple stains to distinguish different types of microorganisms

endotoxin

term for embedded lipid A of gram negative lipopolysaccharide that can cause toxic shock

O-specific polysaccharide

component of lipopolysaccharide that forms a major antigen often used for bacteria serotyping

gram stain

differential stain that differentiates gram positive and negative bacteria based on their cell wall

lipoteichoic acid

polymers of ribitol/glycerol phosphate, covalently attached to the cell membrane and span through entire peptidoglycan layer to reinforce structure, only in gram-positive bacteria

cell wall

structural boundary of cell exterior to the cytoplasmic membrane composed or proteins and polysaccharide chains

murein sacculus

term for entire layer of peptidoglycan that surrounds the entire cell

lipopolysaccharide (LPS)

endotoxic molecule composed of lipid A, polysaccharide, and O-specific polysaccharide extending from outer membrane of gram negative cell walls

teichoic acid

polymers of ribitol/glycerol phosphate that are partially embedded in peptidoglycan to reinforce structure, only in gram-positive bacteria cell walls

gram positive

cell walls composed of thick peptidoglycan layer (10-15+ sheets) reinforced by teichoic and lipoteichoic acids

serotype

an identifiable grouping of bacteria based on external cell molecules, commonly defined by surface sugar molecules that could be other antigens

outer membrane

lipid membrane containing proteins and carbohydrates that surround peptidoglycan layer of gram-negative bacterial cells, contains lipopolysaccharides and lipoproteins

lipoprotein

lipid anchored proteins that link the outer membrane to the peptidoglycan layer and help form the periplasmic space in gram-negative bacteria

glycan

another term for certain polysaccharide, carbohydrate polymer, or long chain of sugars

gram negative

cell wall composed of thin peptidoglycan layer (1-3 sheets) between outer membrane and a cell membrane; has embedded LPS and lipoproteins