Name:____________________________Class:________________Date:__________________
Living or Not?
What is a Virus?
A virus is too small to be seen without a
microscope. A virus is basically a tiny bundle
of genetic material carried in a shell called
the viral coat. Some viruses have an
additional layer around this coat called an
envelope.
SHAPE:
There are thousands of different
viruses that come in many shapes. Many are
multi-sided or polyhedral. If you've ever
looked closely at a cut gem, like the diamond
in an engagement ring, you've seen an
example of a polyhedral shape. Unlike the
diamond in a ring, however, a virus does not taper to a point, but is shaped the same all
around. Other viruses are shaped like spiky ovals or bricks with rounded corners. Some
are like skinny sticks while others look like pieces of looped string. Some are more
complex and shaped like little spaceship landing pods.
REPRODUCTION:
Viruses exist to reproduce only. They can do this only within the body of a living
being. Upon landing on a suitable host cell, a virus gets its genes inside the cell either by
tricking the host cell to pull it inside, or by connecting its viral coat with the host cell wall or
membrane and releasing its genes inside, or by injecting their genes into the host cell's
DNA. The viral genes are then copied many times, using the process the host cell would
normally use to reproduce its own DNA. The new viral genes then come together and
assemble into whole new viruses. The new viruses are either released from the host cell
without destroying the cell or eventually build up to a large enough number that they burst
the host cell.
1. Virus injects itself into the host cell
2. Virus DNA takes control of the host cell
3. Copies of Viral DNA are made using cell material
4. Protein coat and envelope are made using cell material
5. Cell ruptures to release new viruses
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Name:____________________________Class:________________Date:__________________
Where are they found?
Air
Plants
ANIMALS
WATER
Viruses are found on or in just about every material and environment on Earth from
soil to water to air. They're basically found anywhere there are cells to infect. Viruses can
infect every living thing. However, viruses tend to be somewhat picky about what type of
cells they infect. Plant viruses are not equipped to infect animal cells, for example, though
a certain plant virus could infect a number of related plants. Sometimes, a virus may infect
one animal and do no harm, but cause a great deal of damage when it gets into a different
but closely related animal.
VIRUSES CAN INFECT AND DESTROY BACTERIA
Commonly known viruses
BACTERIOPHAGE
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TOBACCO PLANT
VIRUS- (TMV)
HUMAN IMMUNO
VIRUS – (HIV)
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Name:____________________________Class:________________Date:__________________
VIRAL DISEASES
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AIDS
Bovine virus diarrhoea
Bronchiolitis
Cervical cancer (HPV)
Chickenpox
Chikungunya
Common cold
Cowpox
Dengue fever
Ebola
Foot-and-mouth disease
Genital wart
Hepatitis
Herpes
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Japanese encephalitis
Measles
Monkey pox
Mumps
Murray Valley encephalitis
Myxomatosis
Poliomyelitis
Rabies
Rhinovirus
Ross River fever
Rubella
SARS
Swine flu / Influenza
Yellow fever
Viral Infection: Prevention and control
Chemicals known to destroy viruses
Good Hygienic practices,
keeping areas where we live
well ventilated
Behavioural Education
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Healthy body has natural defences that
protect it from infection e.g. interferon a
chemical produced by cells that destroy
viruses
Development of vaccines
and immunisation programs
Controlling Vectors
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Name:____________________________Class:________________Date:__________________
BIBLIOGRAPHY
The above information has been compiled using the following sources
SKC school http://www.edu.pe.ca/southernkings/microvirus.htm 5/9/09
NIAID http://www.stanford.edu/group/virus/retro/2005gongishmail/hiv1.jpg 5/9/09
TheLegenders,RJC,Singapore2001http://library.thinkquest.org/C0123260/basic%20knowle
dge/images/basic%20knowledge/DNA/structure%20of%20bacteriophage.jpg 5/9/09
Allan Burns Emerald city books, 1997, Instant Lessons in biology Book 3, 5/9/09
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