Bacterial structure Flashcards
what 3 organelles do prokaryotic cells lack
- golgi
- ER
- nucleus
genetic material in prokaryotic cells
nucleoid region enclosed in a cell membrane
2 examples of prokaryotes
- bateria
- cyanobacteria
how much bigger are eukaryotes than prokaryotes
10x bigger
3 bacterial shapes
- coccus
- bacillus
- spirochete
cocci info (post-division)
- 2 = diplococci
- chain = streptococci
- cluster = staphlococci
how do most bacilli divide and appear
- divide across their short axis
- appear as single rods
3 external structures in bacteria
- glycocalyx
- flagella
- fimbriae (pilli)
what is glycocalyx
a coating or layer of molecules external to the cell wall –> protective, adhesive, and receptor functions
4 types of flagella
- monotrichoid (1)
- lopotrichois (multiple out one end)
- amphitrichous (1 out each end)
- peritrichious (many all over)
gram + versus gram - structure
- positive: thick peptidoglycan layer (single membrane –> monoderms)
- negative: thin peptidoglycan layer, periplasmic space (double membrane –> diderms)
steps in a gram stain
- fixation
- crystal violet
- iodine
- alcohol decolorizer
- safranin
gram + in a gram stain
- picks up crystal violet
- gets lighter but not decolorized
- stays purple
gram - in a gram stain
- picks up crystal violet
- gets lighter with iodine
- decolorized
- picks up safranin
- turns red
flagella info
- can have any or none
- attached to the cell wall
- provide motility
- composed of glycoproteins
- highly immunogenic
- used for serotyping
- called H antigens
fimbriae (pili)
- smaller protein appendages
- present in higher number on a cell
- not used for motility
- can participate in attachment to host cells
capsules
- outermost layer covering some bacteria
- not easily viewed under gram stain (need india ink or CuSO4)
- virulence factors –> phagocytosis, attachment, desiccation, lysis
spores
- resting stage that enables organism to endure harsh conditions
- transform into active bacteria when conditions improve
- not all bacteria can form spores
methods of sterilization (5)
- heat
- chemicals
- irradiation
- high pressure
- filtration
heat sterilization
- dry heat: coagulates proteins (metal, glass, other solid materials)
- moist heat: coagulates proteins, high penetrating property (culture media, lab items, surgical equipment)
incineration
for infected carcasses
gamma irradiation
- electromagnetic radiation
- disposable plastic lab and surgical equipment
- not for glass or metal
UV light sterilization
- electromagnetic radiation
- used in biosafety cabinets
membrane filtration
used for filtering out bacteria from heat sensitive fluids such as serum, tissue culture media
