BACTERIA AND ARCHAEA
Jess,Alicia,Natalia
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THREE DOMAIN SYSTEM
• The three-domain system is a biological classification introduced by Carl Woese in 1977, that divides cellular life forms into archaea,
bacteria, and eukaryote domains. In particular, it emphasizes the separation of prokaryotes into two groups, originally called Eubacteria
(now Bacteria) and Archaebacteria (now Archaea).
• The current system has the following listed kingdoms in the three domains:
1.
Domain Archaea – prokaryotic, no nuclear membrane, distinct biochemistry and RNA markers from bacteria, possess unique ancient
evolutionary history for which they are considered some of the oldest species of organisms on Earth; traditionally classified as
archaebacteria; often characterized by living in extreme environments. Some examples of archaeal organisms are methanogens which
produce the gas methane, halophiles which live in very salty water, and thermoacidophiles which thrive in acidic high temperature
water.
2.
Domain Bacteria – prokaryotic, consists of prokaryotic cells possessing primarily diacyl glycerol diester lipids in their membranes and
bacterial rRNA, no nuclear membrane, traditionally classified as bacteria. Most of the known pathogenic prokaryotic organisms belong
to bacteria, and are currently studied more extensively than Archaea. Some examples of bacteria include Cyanobacteria
photosynthesizing bacteria that are related to the chloroplasts of eukaryotic plants and algae, Spirochates- Gram Negative bacteria
that include those causing syphilis and Lyme disease, and Firmicutes- Gram-Positive bacteria including Bifidobacterium animalis which is
present in the human large intestine.
3.
Domain Eukarya – eukaryotes, organisms that contain a membrane bound nucleus. An in-exhaustive list of eukaryotic organisms
includes:
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THREE DOMAIN SYSTEM
The three-domain system includes: Eukarya
(represented by the Australian green tree
frog, left), Bacteria (represented by S.aures ,
middle) and Archaea (represented by
Sulfobolus, right)
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CHARACTERISTICS
Archaea Domain: Archaea are prokaryotic cells which are typically characterized by
membranes that are branched hydrocarbon chains attached to glycerol by ether linkages. The
presence of this ether containing linkages in Archaea adds to their ability of withstanding
extreme temperature and highly acidic conditions. Extreme halophiles - i.e. organisms which
thrive in highly salty environment, and hyperthermophiles - i.e. the organisms which thrive in
extremely hot environment, are best examples of Archaea.
Bacteria Domain: Even though bacteria are prokaryotic cells just like Archaea, their
membranes are made of unbranched fatty acid chains attached to glycerol by ester linkages.
Cyanobacteria and mycoplasmas are the best examples of bacteria. As they don't have ether
containing linkages like Archaea, they are grouped into a different category - and hence a
different domain. There is a great deal of diversity in this domain, such that it is next to
impossible to determine how many species of bacteria exist on the planet.
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NUTRITIONAL PATTERN
Archaea- Archaeans dine on a variety of substances for energy, including hydrogen
gas, carbon dioxide and sulfur. One type of salt-loving archaean uses sunlight to
make energy, but not the way plants do it. This archaean has a light-harvesting
pigment in the membrane surrounding its cell. This pigment, called bacteriorhodopsin
(back-tear-ee-oh-row-dop-sin), reacts with light and enables the cell to make ATP, an
energy molecule.
Bacteria- Also like plants, they give off oxygen. Other bacteria absorb food from the
material they live on or in. Some of these bacteria can live off unusual "foods" such as
iron or sulfur. The microbes that live in your gut absorb nutrients from the digested
food you've eaten
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BACTERIA VS ARCHAEA
Archaea
• Ribosomes:
Bacteria
• Ribosomes
-Present
-Present
-No nucleus or organelles
-No nucleus or organelles
• Growth & Reproduction:
• Growth & Reproduction:
-Reproduce asexually through the process of binary fission, budding and
fragmentation.
• Size and Shape:
-Found occurring as rods, spirals, plates, coiled etc.
• Habitat:
• -Extreme and harsh environments like hot springs, salt lakes, marshlands,
oceans, gut of ruminants and humans.
-Bacteria reproduce asexually. Bacteria growth follows in three phases, the lag phase
when cells adapt to new environment, log phase marking exponential growth and
stationary phase when nutrients get depleted.
• Size and Shape:
-Found occurring as rods, spirals, plates, coiled etc.
-Achieve a swimming motility via one or more tail-like flagella
• Habitat:
-Found in soil, hot springs, radioactive waste water, Earth's crust, organic matter, bodies
of plants and animals etc.
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LIFECYCLE- BACTERIA
Lag Phase
• Bacteria do not grow during the lag phase. However, they do adjust to their environment and produce vitamins and amino acids
needed for division. They begin making copies of their DNA, and if the environment supplies enough nutrients, the lag phase may
be very short.
Log or Exponential Phase
• During the log or exponential phase, bacteria multiply rapidly. Under the best conditions, the fastest bacteria can double in about
15 minutes. Other bacteria take days.
Stationary Phase
• During the stationary phase, bacteria growth decreases. If the bacteria moves to another culture, however, rapid growth may
resume.
Death Phase
• During the death phase, bacteria lose all ability to reproduce, which results in death. Like the log or exponential phase, bacterial
death may occur as rapidly as their growth.
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BACTERIA LIFE CYCLE
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BACTERIAL INFECTIONS
How do bacterial infections spread?
• Different bacteria spread in different ways. Examples include:
-through contaminated water (cholera and typhoid fever)
-through contaminated food (botulism, E coli food poisoning)
-through sexual contact (syphilis, gonorrhea, chlamydia)
-through the air, when infected people sneeze or cough (tuberculosis)
-through contact with animals (anthrax, cat scratch disease)
-through touching infected people (strep throat)
How Are Bacterial Infections Prevented?
• Young children commonly get shots of vaccine to prevent bacterial infections
• For many bacterial infections, good living conditions are the best prevention. That means clean water supplies, sanitary disposal of
human waste, well-ventilated housing that is not overcrowded, and prompt medical treatment for people who do get sick.
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TYPES OF BACTERIA
•Escherichia coli (E.coli) - Gram-negative, rod-shaped bacterium commonly found in
the intestines of humans
•Vibrio - genus of Gram-negative bacteria that are rod-shaped, which
•Lactobacillus acidophilus - Lactobacillus acidophilus is a species of the genus
Lactobacillus. It is a rod-shaped bacterium commonly found in human intestines, the
mouth and vagina are found in saltwater.
•Streptococcus - Strptococcus is a genus of Gram-positive bacteria that is spherical in
shape. It is found in the mouth, skin, upper respiratory tract and intestines of humans.
•Clostridium botulinum - Clostridium botulinum is a Gram-positive bacterium that is
rod-shaped and generally found in soil. These bacteria produce neurotoxins that
cause botulism
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TYPES OF ARCHAEA
•Methanogens - anaerobes that produce large amounts of methane gas (CH4)
 important in the carbon cycle
 strict anaerobes - they are poisoned by oxygen
 often used in sewage treatment plants
•Halophiles - "salt-loving" Archaea
 found in such extremely saline locales such as the Dead Sea and the Great Salt Lake
 mostly heterotrophs, but can switch to photosynthesis because of a unique pigment called bacteriorhodopsin
•Thermophiles - "heat-loving" Archaea
 found in hot springs, acidic soils, near volcano vents, etc.
 they use H2S to generate ATP
INTERESTING FACTS ABOUT BACTERIA
http://www.factslides.com/s-Bacteria