Download 2 - Kingdoms Archaebacteria and Eubacteria (P5).notebook

2 ­ Kingdoms Archaebacteria and Eubacteria (P5).notebook
THE LIFE OF A PROKARYOTE
Prokaryotes are single-celled organisms. They are the smallest, simplest
•
organisms.
The group includes:
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Archaebacteria are found in anaerobic and extreme conditions (high
o
[salt], high temperature, and low pH), similar to what are believed to be
the conditions on the early Earth.
Earth's early atmosphere did not contain oxygen, therefore the
§
Early Atmosphere
earliest organisms were anaerobic.
Eubacteria includes the traditional bacteria and is the larger of the
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two.
They are found in nearly every habitat
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studied, including some that no other
organism is able to withstand.
Bacteria have a cell wall and cell
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membrane, but no membrane-bound
organelles such as a nucleus, mitochondria,
chloroplasts, Golgi apparatus, or ER. Some
are covered by a layer of “slime” called
a capsule.
November 02, 2010
Early Atmosphere of Primitive Earth
• Probably H2 and He
-Possibly lost to space because Earth's gravity is not
strong enough to hold lighter gases
• Gases produced were probably similar to those created
by modern volcanoes (H2O, CO2, SO2, CO, Cl2, N2, H2)
and NH3 and CH4.
-No free O2 at this time (not found in volcanic gases).
Back
Characteristics
Primitive Earth
•
.
Some bacteria are able to move using special cell structures called cilia and
flagella.
Hair-like cilia (singular, cilium) and tail-like flagella (singular,
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flagellum) are projections from the cell.
By repetitive beating (like a bending motion), they cause the cell to
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move. Think of oars in a boat. Flagella can propel the cell by waving
back and forth.
If a cell is fixed in place, they can also cause water to move
§
across the surface.
Shapes
Cilia and Flagella
RESPIRATION
Obligate aerobes must have oxygen.
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Obligate anaerobes can not survive in the presence of oxygen.
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Facultative anaerobes will use oxygen if it is present but do not need it.
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NUTRITION
Most are heterotrophic…
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Some are parasites which live off a living host.
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Some are decomposers, feeding on dead organisms and waste.
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Some are autotrophic…
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Either use chemicals as a source of energy (chemoautotrophs) or are
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photosynthetic (photoautotrophs).
REPRODUCTION
Prokaryotes have a single circular chromosome attached to the inside of the
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Single Chromosome
plasma membrane.
Asexual reproduction
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Prokaryotes reproduce by simply splitting in two in a process called
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Binary Fission
binary fission.
The DNA is copied and the cell divides into two identical cells.
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Sexual reproduction
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Sexual reproduction combines genes from two different individuals and
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increases variation. Prokaryotes do not technically reproduce sexually
but can mix genes with one another. Conjugation
Conjugation - Two cells join briefly and one cell donates some DNA
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(called a plasmid) to the other one. Sometimes part of the cell‛s
chromosome is donated as well.
Transformation - Bacteria can also pick up pieces of DNA from the
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environment.
Transduction - Sometimes viruses transfer pieces of DNA from one cell
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to another.
Endospores
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Some bacteria form endospores when environmental conditions become
o
unfavorable. Endospores
Endospores are DNA and a small amount of cytoplasm enclosed in a
tough cell wall. They are resistant to extremes in temperature, drying,
and harsh chemicals.
Mutation is a large source of genetic diversity in bacteria.
o
•
Early symptomatic HIV infection: Mycobacterium marinum infection on the hand Resp/Nutr
Bacterial Pericarditis
Reproduction
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2 ­ Kingdoms Archaebacteria and Eubacteria (P5).notebook
November 02, 2010
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Chromosome
Reproduction
The Eyes of Nye (Antibiotics)
Cell Phones
The Eyes of Nye (Antibiotics)
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