Download Viruses and Bacteria

Viruses and
Bacteria
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COVER YOUR MOUTH
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I. Viruses
A. Is a virus a living organism?
1. All living things are made of cells, able to
grow and reproduce.
2. A virus IS able to do these things but ONLY
inside a host cell.
3. Viruses cause diseases in many organisms.
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B. Discovery of viruses
1. At the end of the 19th century
scientists were trying to find the cause of
tobacco mosaic disease (TMV).
2. In 1935 Wendell Stanley isolated this
virus.
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C. A virus’s Shape is determined by its parts
1. The virus protein coat, or capsid, may
contain either RNA or DNA but NOT both.
2. RNA viruses include HIV, which causes
AIDS, influenza viruses and rabies virus.
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3. DNA viruses include those viruses that
cause warts, chickenpox and mononucleosis.
4. Many viruses have a membrane or an
envelope that surrounds the capsid.
5. The envelope helps the virus enter cells.
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6. It consists of proteins, lipids, and
glycoproteins.
7. Viruses that infect bacteria, called
bacteriophages, have a complicated structure.
8. A bacteriophage has capsid and a tail.
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9. Viruses replicate inside living cells
10. Viruses cause damage when the
viruses replicate inside the cells.
11. Any agent that causes disease is
called a pathogen.
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D. Lytic cycle
1. Virus attaches to a cell and injects DNA.
2. Viral DNA enters the Lytic cycle.
3. New Viruses are made.
4. Cell breaks open and releases viruses.
(destroying the host cells.)
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E. Lysogenic cycle
1. Virus attaches to a cell and inject DNA.
2. Viral DNA enters the Lysogenic cycle.
3. Viral DNA integrates with host DNA.
4. The host cell divides normally
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5. Many cell divisions.
6. The provirus may enter the Lytic cycle, or
stay dominant.
7. Then the DNA enters the Lytic cycle.
8. New viruses are made.
9. Cell breaks open and releases viruses
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4. Viruses have a major impact on the
living world.
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F. Viruses are host cell specific
1. Viruses are often restricted to certain
kinds of cells.
2. Some will affect plants and some will
affect animals.
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G. HIV can replicate in your cells
1. Acquired immunodeficiency syndrome
(AIDS) is a disease in which an individual
is unable to defend his or her own body
against infections.
2. The HIV causes AIDS.
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3. HIV – infected people do not develop AIDS
symptoms until years after infection.
4. HIV infected individuals can feel healthy
and still spread the virus to others.
5. It is transmitted in body fluids, such as
semen and vaginal fluid.
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H. Viruses cause many diseases
1 1. Diseases caused by viruses have been
known and feared for thousands of years.
2. 22 million people died of the flu during
1918-1919.
3. Viruses that evolve are called emerging
viruses.
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4. These new pathogens are dangerous to
public health.
5. Prions are particles that are composed of
proteins and have no nucleic acids.
6. Prions are infectious even though they
contain no genes.
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7. Prions were first linked to a sheep disease
called scrapie.
8. This also causes mad cow disease.
9. A viroid is a single strand of RNA that has
no capsid.
10. They affect plants like cucumbers,
potatoes, avocados, and oranges.
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II. Bacteria
A. Bacteria have a simpler structure than Eukaryotes.
1. Bacteria are prokaryotes they do not have a
nucleus.
2. Bacteria are small!3. Bacteria have only one cell.
4. Bacteria have one single circular DNA.
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5. Bacteria reproduce by binary fission.
6. Bacteria have flagella that move them
around.
7. Bacteria have many different types of
metabolic activities.
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A. The structure
1. A bacterial cell has three shapes.
Bacillus- rod shaped
Coccus- round shaped
Spirillum- spiral shaped
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2. Bacteria can have two types of cell walls,
you can tell this by gram staining.
3. Gram staining is important in medicine
because the two groups of bacteria differ in
how they respond to antibiotics.
4. Some bacteria form thick walled endospores
around their chromosomes and a small bit of
cytoplasm when they are exposed to harsh
conditions.
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5. Pili enable bacteria to stick to stuff
like your skin.
6. Conjugation is a process in which tow
organisms exchange genetic material.
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C. Bacteria are grouped according to
how they obtain energy
1. Photosynthetic bacteria- bacteria that
is able to make food from the sunlight.
They must live in an anaerobic (oxygen
free) environments.
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2. Chemoautotrophic bacteria- they
obtain energy by chemically removing
electrons from material.
3. Heterotrophic bacteria- feed on
organic material and other organisms.
They are aerobic, they need oxygen.
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D. Bacteria cause disease in two basic ways
1. Bacteria can metabolize their host. They
take all the nutrients from the host. ExampleTB
2. Bacteria can cause toxins. Example botulism
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3. Bacterial disease can be fought
4. Antibiotics- fight bacterial infection.
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E. Bacteria are important
1. Food and chemical production- many foods
we eat are processed by specific kinds of
bacteria examples- pickles, buttermilk, cheese,
sauerkraut, olives, vinegar, sourdough bread
and some sausages.
2. Mining and environmental uses of bacteria
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THE END
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