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

• 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