lGelatinous, sticky substance surrounding the outside of the cell

lComposed of polysaccharides, polypeptides, or both

lTwo types

lCapsule

 lSlime Layer

lComposed of organized repeating units of organic chemicals

lFirmly attached to cell surface

lProtects cells from drying out

lMay prevent bacteria from being recognized and destroyed by host

 lIncreases the cell’s ability to cause diseases

lLoosely attached to cell surface

lWater soluble

lProtects cells from drying out

 lSticky layer that allows prokaryotes to attach to surfaces

lResponsible for movement

lLong, whiplike structures that extend beyond surface of cell

lComposed of filament, hook, and basal body

 lFlagellin protein (filament) arranged in chains and forms helix around hollow core

lRotation propels bacterium through environment

lRotation can be clockwise or counterclockwise; reversible

lProkaryotes move in response to stimuli (taxis)

l Runs – movements of cell in single direction for some time; increase with favorable stimuli (positive chemotaxis, positive phototaxis)

 l  Tumbles – abrupt, random, changes in direction; increase with unfavorable stimuli (negative chemotaxis, negative phototaxis)

• sticky, bristlelike projections
• used by bacteria to adhere to eachother, to hosts, and to substances in the environment
• may be hundreds of fimbriae per call
• shorter than flagella
• important function in biofilms

• are hollow, non motile tubes of protein
• one to two pilli per cell
• pilli mediates the transfer of DNA from one cell top the other called Conjugation

• Provides structure and shape and protects cell from osmotic forces
• Assists some cells in attaching to other cells or in eluding antimicrobial drugs
• animal cells do not have walls; so we target call wall of bacteria with antibiotics

• the transfer of DNA from one cell to another

• Most have cell wall composed of peptidoglycan; a few lack a cell wall entirely

• Bacterial cell wall
• composed of sugars (NAG and NAM)
• chain of sugar rotating NAM, NAG
• CHains attached by Tetrapeptide Crossbridges (amino acids)

Gram Positive

Gram Negative

• lRelatively thick layer of peptidoglycan

  lContains unique polysaccharides called teichoic acids

  lSome covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to cell membrane

  lRetains crystal violet dye in Gram staining procedure; appear purple

• Have only a thin layer of peptidoglycan
• Have a bilayer membrane composed of phospholipids, channel proteins (porins), and lipopolysaccharide (LPS)
• May be impediment to the treatment of disease
• Following Gram staining procedure, cells appear pink

• Union of lipid with sugar
• Known as Lipid A
• Is a endotoxin
• Lipid A is released from dead cells when cell wall disintegrates
• may trigger fever, vasodilation, inflamation, shock, and blood clotting
• antibacteruial drugs can trigger release of lipid A

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