Ch 5: Cell Biology of Bacteria and Eukaryotes (Cont.)

lipid A and polysaccharide chains

what are the components of lipopolysaccharide (LPS)?

acts as an endotoxin in lysed cells

what is lipid A?

gram positive has thick cell wall, so the crystal violet and ethanol complex makes peptidoglycan shrink, trapping the purple color

explain process of gram stain (what effect does it have on gram positive?)

ethanol destroys the lipid and crystal violet/iodine complex leaks out

explain process of gram stain (what effect does it have on gram negative?)

capsules

well organized layers made of polysaccharides that are covalently bonded and difficult to wash away

slime layers

polysaccharide layers that are unorganized and easily washed away

glycocalyx

polysaccharide extension that aids in attachment to solid surfaces

s layers

geometric patterns made of protein that aid in protecting from ion and pH fluctuation

protection from phagocytosis, surface attachment

functions of capsules

wax, have to use acid fast stain

what is mycolic acid?

grow slowly

complexity of mycobacteria cell wall makes them

sterols to stabilize

what is in the plasma membrane of mycoplasmas?

DNA replication occurs, protein synthesis and cytoplasm expansion elongates cell, septum forms and cell divides

steps of binary fission

rod (bacilli)

elongates cell wall before septation

cocci

forms chains when they septate in parallel planes

form grape clusters when they septate in random orientations

pili

longer, thicker, less numerous attachment structures

fimbriae

shorter, thin, numerous hairlike attachments

flagella

attachment

swimming motility

rotates like a propeller that is driven by proton motive force

mono

one flagellum on one pole

amphi

one flagellum at each end of cell

lopho

a cluster of flagella at one or both ends

peri

spread over entire cell surface

chemotaxis

rotation of flagella that propels cell in response to stimuli

solid

what type of media is good for separating mixtures of different organisms?

liquid media

what type of media is good for bacteria to move freely?

isolation streaking (dilution) and spread plate

what are the two ways to obtain a pure culture?