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PAP Bacteria and Virus Notes
Ch 19
• Bacteria are grouped into two kingdoms:
-Eubacteria and Arcahebacteria
• -Eubacteria and Archaebacteria have different
membrane lipids and archaebacteria lack the
peptidoglycan found in eubacteria cell walls.
• -Archaebacterial genes are more like those of
eukaryotes than those of eubacteria.
Bacteria are Prokaryotes and have:
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-Cell Wall
-Cell Membrane
-NO nucleus
-Ribosomes
-NO organelles
-Flagella (for
mobile species)
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Bacteria come in three shapes:
Bacillus- rod shaped bacteria.
Cocci- spherical shaped bacteria.
Spirilla- spiral/corkscrew shaped
bacteria
Metabolic Diversity
• Some bacteria are heterotrophs. They
are referred to as chemoheterotrophs.
• As bacteria take in organic molecules
for both energy and a supply of carbon.
• Some bacteria are autotrophs. They
are photoautotrophs if they use light
energy to convert CO2 and water to
carbon compounds. These are often
found near surfaces of lakes, streams,
and oceans.
• Chemoautotrophs can perform
chemosynthesis that perform the same
task as photoautotrophs except they do
not need to use light. They rely on
chemical reactions instead. Many are
found at hydrothermal vents.
Releasing Energy
• Obligate aerobes- require a constant
supply of oxygen
• Obligate anaerobes- must live in the
absence of oxygen
• Facultative anaerobes- Can function with
or without oxygen.
Growth
• _Binary_ Fission is when a bacteria divides in
half producing identical cells. This is asexual
and much simpler than mitosis.
• _Conjugation__- Some bacteria can exchange
genetic information this way when a hollow
bridge forms between two bacteria cells and
genes move from once cell to the other.
SPORE Formation- In unfavorable conditions,
bacteria can form spores that can remain
dormant for months while conditions improve.
Then the bacteria can germinate and grow
again.
Bacteria in the World
Decomposers - Bacteria can help the
ecosystem by breaking down dead tissue.
Very important also in sewage treatments!
Nitrogen Fixers- Bacteria can live in the
nodules of plant roots and fix nitrogen
(nitrogen fixation) which is critical in the
nitrogen cycle.
-Bacteria are also found in our intestines!
They make vitamins that the body cannot
produce by itself and we supply the bacteria
with a warm and safe home. This is a mutual
symbiotic relationship!
• Bacteria can also cause disease in
animals and plants.
• -Bacteria can do this by damaging cells
ant tissues directly.
• -Or bacteria can release toxins that
travel throughout the body and
interfere with the normal activity of the
host.
Virus Characteristics
-Viruses are not considered alive as they do not
have a metabolism or reproduce on their
own.
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-Viruses are composed of DNA or RNA
surrounded by a protein coat called a capsid.
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-If viruses are composed of RNA as their
genetic material, they are called retroviruses
Viral Reproduction:
-In the lytic cycle, a virus enters a cell and
makes copies of itself that causes the cell to
burst.
ANIMATION!
http://www.pgl.ufl.edu/modules/mysterious_invaders/lytic.htm
-In the lysogenic cycle, a virus integrates its
DNA into the DNA host cell, and the viral
genetic information replicates along with the
host cell’s DNA. They do not lyse the host
cell right away.
ANIMATION!
http://www.pgl.ufl.edu/mo
dules/mysterious_invader
s/lytic.htm
Viral Disease
Like bacteria, viruses also can cause
disease by disrupting the body’s normal
equilibrium.
-Unlike bacterial diseases, antibiotics do
NOT work on viruses.
-A vaccine can be used to prevent a viral
disease.
• -Some viruslike particles have been
discovered that also can cause disease.
• -One example is a prion which is a protein
infectious particle and contains no DNA or
RNA (only protein!). This was found to be
the culprit in mad cow disease.