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BCLN BIOLOGY 11 – Rev July 2014
Unit 4 ~ Learning Guide
Name: _______________
INSTRUCTIONS
Using a pencil, complete the following notes and questions as you work through the
related lessons. You are required to have this package completed BEFORE you write
your unit test. Do your best and ask questions about anything that you don't understand
BEFORE you write the unit test.
4.1 NOTES: STRUCTURE OF VIRUSES
Discovery of the Virus
Many human epidemics were well documented and observed in history, but ________
__________________________. The following 3 discoveries shaped our knowledge of
viruses and disease:
1. Jenner's Experiment (1700's).
______________________________________________________________.
He discovered that milkmaids who contracted cowpox and recovered ________
________________________________________________________________
______________________________. On the 14 May 1796, a young milkmaid
called Sarah Nelmes came to see him with blister like sores. _______________
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
____________________________________ which he would inject later. To test
his hypothesis Jenner approached a local farmer and explained that if his theory
was correct, the man's son James would never contract smallpox. Surprisingly,
the farmer agreed. Jenner made two small cuts on James's left arm. He then
poured the liquid from Sarah's cowpox sores into the open wounds which he
bandaged. James got sick with cowpox but once recovered and exposed to
smallpox he did not become ill with the smallpox disease. This was an extremely
risky experiment, but James lived and Jenner had found a way to prevent
smallpox.
Jenner called his idea "___________________________" from the word
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BCLN BIOLOGY 11 – Rev July 2014
vaccinia which is Latin for cowpox. Jenner also introduced the term
______________________.
2. Tobacco Mosaic Virus (TMV)
______________________________
______________________________.
The virus caused a blotchiness on the
leaves of tobacco crops making them
unmarketable and worthless. Solving
this problem was a priority as tobacco
was an important crop in these times.
A German scientist, Adolf Meyer,
suggested that Mosaic disease was
contagious and proposed that the infectious agent was an unusually small
bacterium that could not be seen with a microscope. He tested his hypothesis by
successfully transmitted the disease by spraying sap from infected plants onto
the healthy ones. Using a microscope, he examined the sap and was unable to
identify a microbe.
3. TMV Research Continued
In 1897 a Dutch microbiologist, Martinus Beijerinck _______________________
________________________________________________________________
___________________________________________________. He ruled out
the theory that a filterable toxin such as bacteria caused the disease by
demonstrating that the infectious agent in filtered sap could reproduce.
So what exactly is a Virus???
A virus is a ____________________________________________________________
______________________________________________________________________.
Viruses
_______________________________________________________
and
because of this feature are considered _________________________. In fact, viruses
are ____________________________________________________. Viruses affect all
types of cells, __________________________________________________________
____________________________________________. For example, bacteriophages
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BCLN BIOLOGY 11 – Rev July 2014
___________________________________________________, the tobacco mosaic
virus infects only plants, and the rabies virus only infects mammals. Viruses can be
even more specific than this. Some human viruses even specialize in specific tissue.
Human immunodeficiency virus (HIV) affects specific types of white blood cells and the
polio virus ________________________________________________. Viruses are so
specific because the capsid binds with ______________________ in the host cell's
plasma membrane. If the receptors do not match then the virus cannot attach. Once
attached to a cell, the virus ___________________________ within the host cell for its
own purposes.
Viruses and their relationship to host cells has led to the hypothesis that the
______________________________________________________________________
_________________________________________________________. This statement
suggests that viruses evolved after cells developed. If so, this means that new viruses
are developing all the time. New viruses can develop ___________________________
_____________________________________________. This means that antibodies
produced by the body can work against one type of virus, but might not recognize the
new mutated virus.
Virus Structure
There are _____________________________________
________________________________ to viruses:
1. Proteins forms a structure called the coat or
_______________. The capsid acts as the
protective covering for the nucleic acid it contains.
The proteins in the virus’ capsid must match the
protein markers on the surface of the membrane of
the cell it is trying to invade. As previously stated
this feature is responsible for viral specificity.
2. Nucleic acids - All viruses contain either DNA or
RNA, ___________________________________.
This means that instead of using DNA to control the
activities
of
the
host
cell
_________________________________________
____________________________________________________________
which can then direct the activities of the host cell to reproduce viral particles.
There are many different shapes and types of viruses but, because of the
similarities between bacteriophages and animal cell viruses, the
bacteriophage can be viewed as a model for animal cell viruses. The diagram
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BCLN BIOLOGY 11 – Rev July 2014
above is of a typical bacteriophage.

Head Region - _______________________________________________

The Tail - includes the plug, a ___________________________________
_____________________________________________,
and
the
___________ _______________________________________________
to a bacterial host cell.
Viral Replication
________________ do not reproduce, they ___________________________________
____________________________________________________________. Host cells
______________________________________________________________________
_____________________________________. Viruses are specific to a particular host
cell because part of the capsid binds to the receptor on the host cell's plasma membrane
in a lock and key fashion. The virus then will inject its viral nucleic acid into the host cell
and _________________________________________________________________
____________________________________________________________________.
Replication of Bacteriophages
Bacteriophages are viruses that are parasitic to bacteria. These phages must use
bacteria to replicate. Phages have two types of cycles. In ______________________
_____________________ the virus is replicated within the host cell resulting in
______________________________________________________________
_________
releasing all of the newly formed virus particles. In
the _________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
____________________________________________________________________
sometime in the future.
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BCLN BIOLOGY 11 – Rev July 2014
Reproductive Cycles
1. Lytic Cycle
There are five key stages to the lytic cycle:
i.
__________________________ - capsid combines with the bacteria's
receptor in a lock and key fashion
ii. __________________________ - enzymes from the virus start to eat
away the bacterial cell wall and will inject its viral DNA into the bacterial
cell.
iii. __________________________ - at this stage the virus inactivates the
bacterial genes and takes over the metabolic functions to produce copies
of DNA and produce the capsid.
iv.
__________________________ - during this stage, the viral DNA and
capsids are put together.
v.
__________________________ - lysosomes are made and produce
hydrolytic enzymes to eat a hole in the cell wall of the bacteria. At this time,
the cell will lyse and the newly formed viruses will leave the host cell.
2. Lysogenic Cycle
________________________________________________________________
______________________________, the ______________________________
_________________________________________________, but ___________
_______________________________________________________. During the
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lysogenic cycle, the phage becomes a prophage that is integrated into the host
genome (DNA). At a later time, the phage may start the lytic cycle. When a virus
is latent (i.e., __________________________) it is called a prophage. ________
________________________________________________________________
________________________________________________________________
______________________________________________.

Examples of lysogenic viruses: Herpes, Hepatitis, HIV
YOU SHOULD WATCH THE LYTIC AND THE LYSOGENIC CYCLE
VIDEOS BEFORE PROCEEDING ANY FURTHER!
Retroviruses
Retroviruses are viruses that have the __________________________________,
_____________. These viruses contains an enzyme called _____________________
___________________________________. This enzyme ________________________
_____________________________________________ (in other words, it allows the
RNA to make DNA). __________________________________________________
__________________________________________, which can hide in the host's DNA.
______________________________________________________________________
______________________________________________________________________
______________________________________. An example of a retrovirus is HIV and
some that cause cancers.
Are Viruses Alive?
What are the characteristics of life? How do we define whether something is living
or not? Living things….
1. ___________________________________________________.
2. ___________________________________________________.
3. Require a constant energy supply.
4. ___________________________.
5. ____________________________________.
6. ______________________________________________.
7. Contain enzymes.
8. Can move.
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BCLN BIOLOGY 11 – Rev July 2014
So, are viruses living or nonliving? The following table gives evidence to support each
theory.
Living
Non-living
Viruses have DNA or RNA and protein.
No non-living thing carries nucleic acid.
___________________________________
___________________________________
_____________________________
(slightly different variations)
Viruses do not eat
Viruses display continuity
Viruses do not grow
Viruses have the ability to reproduce
in that one generation follows another
___________________________________
___________________________________
Viruses contain enzymes
Viruses do not reproduce on their own.
Viruses are parasitic
Viruses do not move
Viruses ____________________________________________ things as they do not
exhibit many of the characteristics of life.
Viruses are not classified in the classification system because they are
_______________________________________ and should not be classified with
organisms that are cellular. Viruses are generally smaller than 200 nm in diameter and
can be crystalized.
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4.1 PRACTICE: STRUCTURE OF VIRUSES
1. Viruses are ______________________________________________ parasites
that invade living cells. (1 mark)
2. The type of virus that only invade and infects bacteria are called
________________________________________. (1 mark)
3. Evidence that viruses may have come from living cells is the fact that viruses'
nucleic acids are similar to the host cells' _____________________. (1 mark)
4. Each virus type is _______________________________ to the type of tissue
cells that it invades. (1 mark)
5. Antibodies from last year's flu shot do not work because viruses have the ability
to _____________________________. (1 mark)
6. Viruses are very specific to particular cells because the protein portion called the
capsid binds to the receptor on the host's cell in a ________________________
manner. (1 mark)
7. After the nucleic acid of the virus enters the cell, it takes over the
_____________________________ activity of the cell so that more viruses can
be produced. (1 mark)
8. In the lytic cycle, the host cell must go under ______________________ to
release new viruses. (1 mark)
9. In the ________________________________ cycle, the virus does not
immediately replicate. Replication will take place some time in the future. (1
mark)
10. When the phage is not actively replicating,
_______________________________. (1 mark)
this
means
that
it
is
11. The viral DNA now, now called a __________________________________,
binds with the bacterial DNA and is replicated together. (1 mark)
12. ________________________________________
lysogenic cycle to enter the lytic cycle. (1 mark)
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factors
can
induce
the
BCLN BIOLOGY 11 – Rev July 2014
13. Please label and describe the function of the following viral structures on the
diagram below. Please be neat. (12 marks)
o capsid
o head
o tail fibers
o nucleic acid
o tail
o plug
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4.2 NOTES: VIRAL DISEASES
Viral Diseases
We now know that viruses are considered pathogens that cause disease. We know that
many of these diseases are specific to a particular type of host cell and that viruses are
not considered living as they require this host cell to reproduce. We also know that
viruses cause a large variety of diseases.
Some ________________________________________________ while ____________
_______________________________________________________________________
_______________________________________________________________________
_____________________________________________________________. Some new
antiviral medications are being developed but are only used in special circumstances at
this time.
Viral pathogens are newsworthy. You may
recognize the ones in the list below. You
will notice that there is a lot of variety in the
structure and function of these viruses. This
variety is not a surprise as viruses have
been evolving for a very long time along
with the cells they infect.
The side photo is a micrograph of an
Adenovirus that causes the common cold.
You know the symptoms.
Photos below are of Smallpox which causes high fever and the formation of small
blisters on the skin. ______________________________________________________
_____________________________________________________________ (1970's).
Let's hope it stays that way as vaccinations ceased in the 1980's.
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Photos below are of the Polio virus which is transmitted through direct contact and feces
and the IRON LUNG. Polio destroys nerve cells and causes paralysis. It may well be the
next viral disease eliminated by a vaccine.
Hanta Virus
Hanta
virus
____________________________________
_________________________. The result is _________
___________________________________________________
______________________________. There is no vaccine so
avoid contact with mice!
West Nile Virus
West Nile virus is transmitted __________________________
_________________________________________. The virus
______________________________________ (encephalitis).
There is no vaccine so avoid contact with mosquitoes.
__________________________________________________
__________________________________________________.
HIV (Human Immunodeficiency Virus)
__________________________________________________
__________________________________________________.
Transmission of the virus is ________________________
___________________________. It is estimated that 50 million
people are infected worldwide. There is no vaccine but there
are effective drugs that can slow the disease but not cure it.
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Ebola
Ebola was first recognized in 1976. It is _________________
_________________________________________________
________________________________________________.
There is no vaccine but outbreaks have been controllable although there is a major outbreak as this is being written
(July 27, 2014) in West Africa with over 700 cases and 600
deaths confirmed. This virus is often the source of inspiration
for movies such as "Outbreak".
Preventing Viral Diseases
Antibiotics are __________________________________________. Antibiotics are
designed to disrupt the metabolism of organisms. They work on bacteria but _________
______________________________________________________________________
_____________________________. The best way to stop viral infections is to prevent
them from getting into the body to find a host cell.
The term ____________________________ is often used to describe the degree to
which a particular pathogen is infectious.
The human body has 3 major lines of defense against disease caused by viruses and
bacteria:
1. The primary line of defense is made up _______________________________
____________________________. These barriers include: skin, hair, earwax,
boogers, saliva, stomach acid, cilia in the throat, mucus, tears, oil, etc.
The first line of defense is almost always enough to stop invaders. However,
________________________________________________________________
and the pathogens are able to move inside the body.
When this happens ________________________________________________
__________________________________________________________________
_________________________________________. These are the secondary and
tertiary lines of defense.
2. The secondary line of defense is made up of Phagocytic white blood cells that
deactivate and then engulf the viruses destroying them. When the secondary line
of defense cannot destroy the invaders the tertiary line of defense is activated.
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3. The tertiary line of defense is made up of _______________________.
________________________________________________________________
_____________________________. The antibodies find the chemical signal the
antigen is excreting and latches on to it. Different pathogens have different
markers. Antibodies are made specific to each marker. B-Cells (_____________
_____________________________________________) release antibodies that
tag the incoming virus for destruction. _____________________________
_______________________________________________________________
_______________________________________. Viruses are destroyed later by
phagocytic white blood cells.
Additional defense against viruses
_______________________ are produced by virus ____________________________.
_______________________________________________________________________
_______________________________________________________________________
_________________________________. Interferons slow (interfere with…hence
interferon) viral infection and allow WBCs and antibodies to respond.
As well, __________________________ are chemicals that _____________________
_________________________________ (cell-eating WBCs) in the blood. Pathogens
are engulfed and digested by the phagocytes.
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BCLN BIOLOGY 11 – Rev July 2014
Achieving Immunity
___________________________________ are used to produce immunity against
pathogens. It is the process of infecting a person with a _________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________.
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BCLN BIOLOGY 11 – Rev July 2014
4.2 PRACTICE: VIRAL DISEASES
1. Why are antibiotic useless against viruses? (2 marks)
2. Please list at least 3 ways we can prevent viral infections from spreading. (3
marks)
3. Please pick one of the following topics to write a 1 page paper (~ 250 words)
about. Please use the internet to research the topic. DO NOT PLAGERIZE!
Attach completed assignment to and submit with the learning guide. (20 marks)
a. Vaccinations and how they work
b. Viral Disease (choose one…be sure it is VIRAL)
 identify name of virus
 identify name of disease caused by virus
 identify general structure of virus (RNA, DNA, enveloped, helical)
 mode of transmission (i.e., airborne, body fluids…)
 effects/symptoms
 treatments
 who it affects, where and when (history of outbreaks)
c. Compare and contrast the replication cycle of a biological virus versus a
computer virus.
~ END OF BIOLOGY 11 UNIT 4 LEARNING GUIDE ~
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BCLN BIOLOGY 11 – Rev July 2014
UNIT 4 ANSWER KEY
4.1 PRACTICE: STRUCTURE OF VIRUSES
1-12. Answers are not provided for fill-in the blank questions.
13. Please label and describe the function of the following viral structures on the diagram below.
Please be neat. (12 marks)
o
o
o
o
o
o
capsid
head
tail fibers
nucleic acid
tail
plug
Capsid = protein coat that protects the viral genetic
material (DNA or RNA) and allows virus to attach to
host cells.
Head = capsid + viral genetic material (nucleic acid)
Tail fibers = help virus to attach to host cell
Nucleic acid = DNA or RNA, is the viral genetic
material that encodes for the viral proteins
Tail = sheath + plug + tail fibers
Plug = hollow tube that nucleic acid passes through
to go from virus into host.
4.2 PRACTICE: VIRAL DISEASES
1. Why are antibiotic useless against viruses? (2 marks)
Antibiotic directly translates to "against life" and are used to kill living cells by
targeting some component or function that is necessary to sustain life. As virus are
not living, antibiotics cannot limit the spread of viruses.
2. Please list at least 3 ways we can prevent viral infections from spreading. (3 marks)
Wash our hands. Eat well and get plenty of sleep so that our immune systems are in
prime working condition to fight off viral infections. Vaccinations.
3. Answers will vary depending on topic chosen.
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