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Bacteria (Prokaryotes)
Chapter 27
What you need to know!
• Different Domains and Kingdoms of
prokaryotes
• How chloroplasts and mitochondria
evolved through endosymbiosis
Domains and Kingdoms
• Bacteria  Eubacteria
• Archaea  Archaeabacteria
Characteristics of Both
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Prokaryotes
Evolved all metabolic pathways on earth
No membrane bound organelles
Smaller ribosomes
Haploid (no meiosis)
Can have plasmids
Can have flagella (made of flagellin not
tubulin)
• Classified based on: metabolism then shape
then staining
– Autotrophs: photosynthetic and chemosynthetic
– Heterotrophs: parasites, saprobes (decomposers),
and photoheterotrophs (use photosynthesis and
consume food)
Archaeabacteria
• Methanogens: anaerobic, heterotrophic,
produce methane, found in: mud, swamps,
guts of cows, and termites
• Extreme Halophiles: aerobic, heterotrophic,
or anaerobic, photosyntheitc (with pigments),
live in high salinity (Salt Lake, Dead Sea)
• Thermoacidophiles: chemosynthesis,
autotrophs, live in high heat (150 – 180
degrees F) and acidic environments (pH 2),
hot springs, sulphur vents
Eubacteria
• Endospores: DNA packed into cell wall for
long term hybernation/survival
• Identified by shape: cocci (sphere), bacilli
(rod), spirilla (spirals)
• Distinguished by staining method
• Cyanobacteria (formerly blue/green algae):
photosynthetic, some fix nitrogen
• Chemosynthetic bacteria: autotrophs, some
fix nitrogen
• Nitrogen Fixing Bacteria: heterotrophs,
mutualistic with plants, live in modules
• Spirochetes: spirilla, move in a corkscrew
motion
Endosymbiotic Theory
States that mitochondria (M) & chloroplasts (C) were
prokaryotic organisms that were swallowed by another larger
prokaryote 3-4 byo through a process called endocytosis. M
& C were not digested but formed a: mutualistic symbiosis
with their host.
Endosymbiotic Theory
Arguments that support ET
1. M, C, and N have their own DNA
2. M and C DNA is similar to prokaryotic
DNA
3. M and C multiply independent from
nucleus/mitosis
4. M, C, and the Nucleus have double
membranes
Oxygen? Yes or No
• Obligate aerobes: need oxygen
environment to live
• Obligate anaerobes: need an oxygen free
environment to live (absolutely no oxygen)
• Facultative anaerobes: can survive w/ or
w/out oxygen