Download The Discovery of Viruses

Chapter 20.1 Viruses
Goal: To learn the structures of viruses and
prokaryotes, how they reproduce and their effects on
the human body
The Discovery of Viruses

A virus is a nonliving particle made up of ____________,
__________ __________ and sometimes lipids.
Structure and Composition

Viruses are extremely small; and can only be seen with an
____________ microscope.

The ___________ makes up the protein coat of a virus. Most
animal viruses, like influenza, also have an additional coat of
phospholipids.

Viruses can have a _______ genes or ______________ of genes.

Viruses have proteins on the surface of their membrane and use
them to ___________ to other cells they infect. The proteins on
the virus __________ the host cell into letting the entire virus in
or just its _____________ material.

Viruses are very specific meaning plant viruses typically
infect____________, animal viruses infect certain species of
___________ and bacterial viruses only infect certain types of
______________.

A _____________________ is a virus that infects bacteria.
Make a diagram using Figure 20-1 Viral Forms
T4 Bacteriophage
Tobacco Mosaic Virus
Influenza Virus
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Viral Infections

Once inside a host cell the virus will use its genetic material to
take ____________of the cell and make multiple _________ of
the virus.
Lytic and Lysogenic Infections

There are two types of infection; ________ infections and
_____________ infections.

A lytic infection occurs when a virus enters the cell, makes copies
of the virus and causes the cell to ___________.

A lysogenic infection occurs when a virus enters a cell and doesn’t
take over the cell ______________but will later cause disease.
The viral DNA that becomes imbedded into the hosts DNA is
called a ________________.
Make a diagram using Figure 20-3
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A Closer Look at Two RNA Viruses

70 percent of viruses contain _______ rather than _______.

Human RNA viruses include the common cold, HIV and even some
forms of ___________.

A virus that uses its RNA to make DNA is known as a
____________. HIV is an example of a retrovirus.

Viruses are ______________ since they depend entirely on other
living things for their existence and often harm the host.
Outline the Common Cold Infection Mechanism from page 578
Outline the HIV Infection Mechanism from page 578
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Use the Venn diagram to list the similarities and differences
between viruses and cells. Use the chart on page 579 to complete
the diagram.
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20.2 Prokaryotes
Classifying Prokaryotes

Prokaryotes are single celled organisms
that lack a __________ so their DNA is in
the cytoplasm.
Bacteria and Archaea

Prokaryotes are classified into ___________ and ____________.

Bacteria are found everywhere on earth.

Bacteria have a _________ _________ made up of sugars and
amino acids called a ___________________ that surrounds the
cell membrane.

Some bacteria have _____________ for movement and
_________to anchor to surfaces.
Make a diagram using Figure 20 – 7
Typical Bacterial Structure

Archaea look similar to bacteria but their cell walls lack a
________________ and their DNA sequences (genes) are more
similar to _______________than bacteria.
Archaea produce methane gas and live in ____________ environments
that may contain little to no oxygen such as bogs and the digestive tracts
of animals. Some Archaea live in extremely salty environments or in hot
springs that approach the boiling temperature for water.
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Structure and Function
Size, Shape, and Movement

Prokaryotes differ in their shape, movement and the way they
obtain their _____________.

Bacteria come in three shapes; _____________ (bacilli),
_____________shaped (cocci) and____________ shaped (spirilla)

Some bacteria do not move at all while some have ____________
to help propel on a gel like substance they secrete.
Nutrition and Metabolism
Use figure 20 -10 on page 582 to show the varied ways prokaryotes
obtain and release energy.
Energy Capture by Prokaryotes
Mode of
|Nutrition
How Energy Is
Captured
Habitat
Example
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Energy Release by Prokaryotes
Mode of
Metabolism
How Energy is
Released
Habitat
Example
Growth, Reproduction and Recombination

____________ ____________ is a type of asexual reproduction
that occurs when a cell doubles in size and then divides in half
creating two identical cells.

Binary fission is considered to be a form of____________
reproduction since there is no exchange of ____________
material.

Binary fission happens very rapidly and can occur as quickly as
every 20 minutes.

When the environment is unfavourable some prokaryotes can for
an ___________. An endospore has thick walls protecting the
___________and cytoplasm and this allows the prokaryote to stay
______________ for long periods of time until the environment
becomes more favourable.
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
Genetic variation can occur two ways even though prokaryotes
reproduce asexually. One method is when a mutation in their
_________ occurs and the mutation is passed on to a daughter
cell. Another method is through _____________ where a hollow
bridge forms between two cells and a ___________ (ring of DNA)
is transferred. The transfer of genetic material ____________
genetic variation in the population.
The Importance of Prokaryotes
Decomposers, Producers, Nitrogen Fixers and Human Use

Prokaryotes play an important role in maintaining the ecological
balance of the environment.

Prokaryotes break down or ______________ dead organisms and
by doing this they provide the raw materials for other organisms
to use. ___________________ are also important in sewage
treatment plants, purifying water and chemicals used in fertilizing.

Photosynthetic prokaryotes are the most abundant primary
__________________ in the environment.

Prokaryotes have the ability to fix _____________ from the
environment and turn it into a useful form so other organisms can
turn it into ________________ and other molecules.

Humans use prokaryotes to produce yogurt, digest petroleum and
remove wastes and poisons from water.
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20.3 Diseases Caused by Bacteria and Viruses
Bacterial Diseases

________________ are disease causing agents.

Louis Pasteur was the first to discover that bacteria cause disease
and he established the ___________ ___________ of disease.
Disease Mechanisms

Bacteria produce disease in one of two ways:
______________ Tissue

Bacteria will enter the body and begin to grow and this results
in an ____________ response that destroys large areas of
tissue.
_____________ Toxins

Bacteria will produce _________ (poisons) that will travel
through the body and damage tissue, blood vessels and
organs.
Finish the following chart on Controlling Bacteria
Physical Removal
Using a refrigerator to keep foods
at low temperatures.
Disinfectants
Heating instruments at
temperatures above 1000 C
Food Processing
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Preventing and Treating Bacterial Infections

Bacterial infections can be prevented by receiving a
________________. A vaccination is made of weakened or
dead pathogens which are injected into the body to cause an
_______________ response to that specific pathogen. Some
vaccinations will protect you for years or a life time.

_______________ are used to treat bacteria. They disrupt the
production of the cell membrane and cause the bacteria fall
apart.
Viral Diseases
Disease Mechanisms, Preventing and Treating Viral
Infections

Viruses attack and destroy certain cells in the body. Viruses will
also affect the ______________ and development of cells and at
times cause ____________.

Viruses can be prevented by using __________________, hand
washing, avoiding contact with sick individuals and coughing into
a tissue or sleeve.

Viruses cannot be treated with __________________ but there
are several antiviral drugs that attack specific viral
_______________.
Emerging Diseases
Superbugs and New Viruses

An unknown disease that appears for the first time or a wellknown disease that becomes difficult to treat is known as an
______________ ______________.

With the increased ability for people to travel and produce being
shipped around the globe there is a greater possibility of
spreading new diseases.

The danger of emerging diseases is that people have little to no
_________________.
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
The widespread use of _____________ has led to natural
selection that favours bacteria that are resistant to antibiotics.
Common bacteria have become ____________ _________
resistant making them very difficult to control especially when
they are spread very easily.
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