ch 3 Cell Wall

sacculus

-bacterial cell wall -consists of a single interlinked molecule that envelops the cell -unlike membrane is a single molecule cage like structure -grows with a twist incorporating new units of peptidoglycan in a helical curve

Gram Positive cell envelope

-multiple layers of peptidoglycan are reinforced by teichoic acids -negativily charged cross threads of teichoic acids and thickness of cell wall help retain gram stain -outside cell wall cells are encased in capsule

peptidoglycan

-what most bacterial cell walls are composed of -murein (synonymous)

Gram positive vs. Gram Negative Bacteria

Gram positive: thick cell wall with multiple layers of peptidoglycan threaded by teichoic acids. Gram Negative: a single layer of peptidoglycan covered by an outer membrane, cell membrane called the inner membrane

capsule

composed of polysaccharide and glycoprotein filaments, protects cells from pagocytosis wither gram + or gram -can have

Bacterial cytoskeleton

includes proteins that regulate cell size, play role in determining rod shape of bacilli

glycan

peptidoglycan consists of parallel polymers of disaccharide

Peptidoglycan in archea?

peptidoglycan is unique to bacteria even though some archaea build similar structures who's physical nature is similar

Gram Negative outer membrane

regulates nutrient uptake and excludes toxins. The out membrane contains LPS and protein porins of varying selectivity

S layer

surface layer commonly found in free living bacteria and archaea -thick sub unit of proteins w/ attached sugars -rigid, but also allows substaces to pass through it in wither direction -in archae it serves at cell wall

cross bridges

the peptide extension can form these connecting parallel strands of glycan