bacterial cell structure

3 domains

Eukarya, Bacteria, Archaea

eukaryote

organism that consists of one of more cell which have a nucleus and developed intracellular compartments

bacteria

includes a lot of prokaryotes, usually a few um long

archaea

similar to bacterial size/structure but different molecular organisation, usually found in unusual habitats

virus size

0.01-0.2 micrometers

bacteria size

0.2-5 micrometres

eukaryotes size

5-100 micrometres

yeast size

5-10 micrometres

algae size

10-100 micrometres

protists size

50-100 micrometres

all cell properties

metabolism, growth, evolution

some cell properties

motility, differentiation, communication

glycosylation

process which covalently attaches a carbohydrate to a macromolecule

bacterial cell components

cytoplasmic membrane, cell wall, s-layer, capsule/slime layer, nucleiod, inclusions, ribosomes, flagellum

bacterial cell wall

peptidoglycan - polymer of modified sugars, crosslinked by short polypeptides

bacterial cell shapes

cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped)

diplococci

pairs of cocci

streptococci

chains of cocci

gram positive cell wall

90% peptidoglycan, lipoteichoic acid

gram negative cell wall

thin peptidoglycan layer, lipopolysaccharide, contains a periplasm and porins, more complex than positive

periplasm

matrix between inner cytoplasmic membrane and bacterial outer membrane

capsule

sticky outer layer which allows prokaryote to stick to others and protects against dehydration

mycobacteria

contains mycolic acid, arabinogalactan, extractable phospholipids

archaeal cell wall

no peptidoglycan, s-layer, pseudomurein

gram stain process

stain with crystal violet, rinse, iodine, wash with ethanol, rinse, add safranin and blot

gram positive gram stain

stays violet - peptidoglycan traps crystal violet

gram negative gram stain

pink/red - dye is rinsed from peptidoglycan

fimbriae

short, thin hairlike structure which recognise and attach to surfaces, many per cell

pili

similar to fimbriae but thicker, longer and fewer

required for mating

flagella

extended pili for locomotion and attachment

monotrichous

one flagella

amphitrichous

one flagellum at each end of cell

lophotrichous

cluster of flagella at one or both ends

peritrichous

flagella all over

nucleiod

irregular shape, location of 1/2 chromosomes

inclusions

granules of material reserved for future use, storage, gas vesicles etc

endospores

made by gram positive bacteria, resistant to harsh conditions, can survive 100s of years, contain calcium dipicolinate which can dehydrate cells, contains chromosome copy, metabolism stops and endospore is released

prokaryotic genome

one circular chromosome, located in nucleiod, may have plasmids