Microbiology Chapter 4: Functional Anatomy of Prokaryotic and Eukaryotic Cells

prokaryote

prenucleus cell lacking organelles and containing a small circular chromosome with no membrane or histones. contains peptidoglycan cell walls and divides by binary fission

eukaryote

true nucleus cell containing organelles, DNA in nucleus, chemically simple cell walls, and cell division by mitosis

coccus

spherical shaped bacterial cells

bacillus

rod shaped bacterial cells

glycocalyx

viscous (sticky), gelatinous polymer surrounding prokaryotes composed of polysaccharides and/or polypeptides; protects from phagocytosis, enables adherence to surfaces, prevents desiccation, and may provide nutrients

capsule

glycocalyx that is organized and firmly attached to the cell wall; protect pathogenic bacteria from phagocytosis from the cell’s host

slime layer

glycocalyx that is unorganized and only loosely attached to the cell wall

flagella

long filamentous appendages that propel bacteria; may be at polar ends OR distributed across entire cell; composed of filament, hook, and basal body

taxis

movement of a bacterium toward or away from a particular stimulus; flagella allows this

H antigen

flagellar protein useful for distinguishing between variations of a species

archaella

flagella-like structures anchored to motile archaea cells consisting of glycoproteins called archaellins

axial filaments

bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell; movement in a corkscrew motion

fimbriae and pili

hairlike appendages for gram-negative cells that are shorter/straighter/thinner than flagella

fimbriae function

involved in forming biofilms on surfaces and help bacteria adhere to surfaces on the body

pili function

involved in twitching and gliding motility as well as conjugation (bringing bacteria together and allowing for the transfer of DNA)

gram-positive cell wall

thick peptidoglycan layers with teichoic acid

gram-negative cell walls

thin peptidoglycan and an outer membrane made of lipopolysaccharides, lipoproteins, and phospholipids; outer membrane protects from phagocytosis, penicillin and chemicals while protein porins permit beneficial molecules to come in

lipopolysaccharides

large complex molecule containing lipid A, a core polysaccharide, and an O polysaccharide

atypical cell walls

mycoplasma: no cell wall, sterols in their membrane

archaea: wall made of pseudomurein

acid-fast cell walls: mycolic acid over a thin peptidoglycan layer