1. Bacteria are microscopic, unicellular, prokaryotic organisms that live in nearly
every environment on earth. Some species are heterotrophs & some are
autotrophs. Shapes include round - coccus, rod - bacillus, spiral - spirillum.
2. Kingdom Archaebacteria:
a) there are a few 100 species of these “ancient” bacteria that live in
extreme habitats where there is usually no oxygen such as: swamps,
deep-ocean volcanic vents, salt lakes, & hot springs
b) biochemical makeup cell membrane & complex genetic makeup make them
unique to other prokaryotes
c) autotrophic species use chemicals such as salt or methane gas food energy
in a process called chemosynthesis
e) heterotrophic species in sewage lagoons play a role in decomposition &
recycling of organic matter
3. Kingdom Eubacteria:
a) more than 10,000 species live in most habitats except extreme ones
b) strong cell walls & a less complex genetic makeup make them unique
c) some heterotrophic species are disease-causing pathogens - they release
poisonous toxins - use of antibiotics/antiseptics interferes with growth

d) cyanobacteria in ponds, streams, & mud contain chlorophyll to trap sun’s
energy to produce food energy with photosynthesis
e) nitrogen-fixing bacteria are chemosynthetic autotrophs - they convert
atmospheric nitrogen in soil into nitrogen compounds plants can use
f) other beneficial species are used to produce foods (cheese, pickles,
yogurt) & medicines (antibiotics)
4. Structural details of bacteria:
a) cell membrane is surrounded by cell wall & some also have a capsule
b) extensions called pili are used for attachment or tranfer of genetic
material & flagella are used for movement
c) floating in cytoplasm is bacterial DNA arranged as a single, circular
chromosome - may also have small loops of DNA called plasmids
d) when conditions are unfavorable some species enclose their DNA in an
endospore until favorable conditions return & growth begins again
(extreme temperatures, harsh chemicals, radiation, drying, etc.)
5. Bacteria can reproduce millions of new cells weekly:
a) asexual reproduction - binary fission - DNA replicates & cell divides to
create 2 genetically identical copies
b) sexual reproduction - conjugation - 1 bacterium transfers all or part of
its chromosome to another bacterium