Lesson 4: Domain Bacteria and Archaea Flashcards
Domain Bacteria
(Eubacteria)
A large and diverse group of
organisms that consist of
prokaryotic cells.
These are cells that have
no nucleus
The cell walls contain the
protein peptidoglycan
Grow everywhere on earth
Types of Bacteria
The simplest way to classify
bacteria is by cell shape
Cocci – round (singular
coccus)
Bacilli – rod – shaped
(singular bacillus)
Spirilla – spiral – shaped
(singular spirilum)
Bacteria often grow in
characteristic patterns, or
groupings.
The prefix diplo- describes cells
arranged in pairs
The prefix staphylo- describes
cells arranged clusters
The prefix strepto- describes
cells arranged in a chain
Bacterial Respiration
Obligate aerobes - need a constant O2
supply
Microaerophile – need a very low
concentration of oxygen (<21%)
Obligate anaerobes - must live in the
absence of O2
Facultative anaerobes - use
fermentation of organic molecules for
energy like obligate anaerobes do but
are not harmed by oxygen.
Bacterial Energy Production
Autotrophic
Phototrophic autotrophs – use light energy to produce carbohydrates
Chemotrophic autotrophs – use inorganic chemicals such as hydrogen
sulfide, nitrates ammonia, sulfur and iron as energy
Heterotrophic
Chemotrophic heterotrophs – break down organic molecules for energy
Photosynthetic heterotrophs – can obtain energy either through
photosynthesis or the breakdown of organic molecules
Importance of Bacteria
Food Production
Ex. cheese, yogurt, buttermilk, sour cream, and
sauerkraut
Industry
Ex. petroleum digestion, waste and poison
removal, mining minerals, and drug synthesis
Human Symbiosis
Ex. intestinal bacteria to digest cellulose or
produce vitamins (in humans bacteria produce
vitamin K in the large intestine)
Bacteria and the
Environment
Bacteria fill the ecological role of decomposer.
Bacteria that recycle and decompose (break
down) dead material can be called
saprophytes.
Sewage decomposition is accomplished
largely by encouraging and controlling
bacterial growth. The products are H2O, N2,
CO2, and solid leftovers that can be used to
fertilize crops.
Nitrogen fixation is accomplished in nature
only by cyanobacteria notably Rhizobium in
root nodules of legumes. These live
associated with many types of plants and
convert N2 from the air into a form plants can
incorporate into amino acids.
Domain Archaea
Discovered in 1977 and originally classified as
bacteria.
Classified as their own domain in 1990
Like bacteria, this group of organisms consist of
prokaryotic cells
Are biochemically different than bacteria
Live in extreme environments (considered
extremophiles)
Extreme heat (>100ºC)
Acidic and Alkaline Environments
High Salinity (high salt concentration)
Extreme Pressure (up to 200 atmospheres)
Produce methane gas
Obligate anaerobes
