Bacteria
General Characteristics
• Prokaryotic: single-celled organisms that lack
nuclei & about 1-5 microns in size
• Move about using cilia or flagella
3 Basic shapes
• Bacilli (rod shaped)
• Spirilla (spiral shaped)
• Cocci (round shaped)
• Autotrophic: either photoautotrophic or
chemoautotrophic
• Heterotrophic: aerobic, anaerobic, or
facultative anaerobic (live with or w/o
oxygen)
Reproduction
• Asexual reproduction: binary fission,
replication of DNA then divides in half.
• Sexual reproduction: conjugation, where
they swap DNA
• In unfavorable conditions, Endospores
are formed where DNA is enclosed in a
protective “shell”.
Bacteria Clock
Bacteria in Nature
• Decomposers: break down dead &
decaying matter. Recycles nutrients
into the environment.
• Fix nitrogen for soil
• Purifies water
• Produces CO2 for animals and plants
Bacteria & Desease
• Few actually cause disease.
• They are called Pathogens: disease causing
agents
• Two ways bacteria cause disease: damage &
toxins
– Heterotrophic bacteria damage cells and tissues
– Metabolic waste can be a toxin and travels
throughout the body and poisons you. See
Botulism in the book.
Controlling Bacteria
• Antibiotics: blocks the growth & reproduction
of bacteria
• Sterilization by heat or chemicals kill most
bacteria.
• Archaebacteria are ancient bacteria and are
sometimes called extremophiles. These
things live in extreme thermal or chemical
areas. What could control these types of
bacteria?
Beneficial Bacteria
• Food: yogurt, cheese, sauerkraut, etc.
• Industry: digest petroleum products
which is good for environmental
cleaning efforts, and many others.
• Makes drugs & medicines.