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Prokaryotes
Classification
2 kingdoms
Identificaiton
Bacteria
 unicellular
 no nucleus or organelles
 cell membrane and cell wall (no cellulose)
 Eubacteria: “true” bacteria
 found land, water, on and in us.
 e.g. Echerichia coli (gut)
Clostridium tetani (tetanus)
 archaebacteria: “ancient” bacteria
 found in harsh environments
 e.g. methanogens (marshes)
halophiles (Great Salt Lake)
thermophiles (hot springs)
 shape: rod-shaped, spherical or spiral
 cell walls: w/ or w/o carbohydrate (peptidoglycan)
 movement: no movement, glide, spiral, snake.
Taking in
Energy
 most are heterotrophs
 take in organic molecules (carbon, energy)
 some can also photosynthesize
Releasing
Energy
 autotrophs
 capture light energy in carbon compounds.
 cellular respiration or fermentation
 obligate aerobes: need oxygen to live.
 M. tuberculosis (tuberculosis)
 obligate anaerobes: must have NO oxygen to live.
 C. botulinum (canned foods)
Growth and
reproduction
 facultative anaerobes: can live w/ or w/o oxygen
 E. coli (human gut or sewage)
 can divide very quickly (up to every 20 mins.)
 binary fission: mitosis to form 2 daughter cells.
 conjugation: exchange genetic info
 spore formation: thick walls to survive adverse
conditions
Importance
 decomposers break down dead organic material
 nutrient recycling in environment
 sewage treatment
 nitrogen fixers change N2 gas to usable forms (NH3)
 bacteria in nodules on roots of legumes
 Rhizobium spp. on soybeans, beans, peas.
 many human uses
 health
 gut, mouth and skin bacteria
 probiotics restore gut flora
 medicines synthesized:
 e.g. insulin, growth factor, botox
 genetic, biotech research
 industry
 clean oil spills
 clean toxic water
 biofuels
 agriculture
 B. thurengensis: insect control
 nitrogen fixation
 food preservation
 yoghurt, cheese, wine, beer, vinegar
 pickles, sour kraut, sour dough
Disease
 some bacteria act as pathogens (cause disease)
 use cells as food
 tuberculosis destroys lung tissue
 produce toxins
 streptococcus: toxins cause scarlet fever
 prevention
 vaccine: weak or killed strain of pathogen
 immune system activated
 antibiotics: block growth and reproduction
Controlling
bacteria
 heat sterilization: kills bacterial cells
 disinfectants: soap, bleach, etc.
 refrigeration: slows bacterial growth