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Viruses
Viruses do not have a kingdom of their own, because they are non-living.
Viruses are not cells, since they are not alive. They are small, non- living
particles that invade and multiply in a living cell, (Host) which provides the
virus with a source of energy. Viruses need energy to multiply. Viruses can
only multiply when they are inside a living cell.
All viruses act like a parasite because they live on or in host and cause harm
to the host. Viruses can infect all the six kingdoms, but they can only infect
few types of cells in a few specific species.
Naming Virus:
Since viruses are not alive, scientists do not use binomial nomenclature to
name them. Instead they are named after the scientist who identify them, or,
the organism they infect or the place it is found.
Shapes and Sizes of Viruses
Viruses vary widely in shape from round, rod like, thread like to complex
structures like a robot. Bacteriophage is virus that infects bacteria and
sometimes is also called as “ Bacteria eaters.” It has a complex structure that
looks like a robot.
Viruses vary in size. Viruses are smaller than cells and are measured in
nanometers.
Structure of a Virus
Although viruses have different shapes they have the same basic structure.
All viruses have two basic parts: An outer coat made up of Protein that
protects the virus and helps it to attach to the host and the inner core made
up of genetic material that contains the instructions for making new viruses.
Virus Multiplies
After a virus attaches to a cell it enters the cell. The genetic material takes
over the cell’s functions. Some viruses take over immediately while some
wait for a while.
Active Virus:
After entering, an active virus immediately goes into action. The genetic
material takes over and begins producing the genetic material and the virus’s
protein. Then the parts assemble to form new viruses. The host cell bursts
open when the cell is full of virus and releases the new cell.
Hidden Virus
Some Viruses enter the cell but remain non- active for a while. The genetic
material enters the host and becomes part of the cell’s genetic material.
The Virus does not affect the cell’s functions. The genetic material stays
inactive for a long time. The genetic material of the virus suddenly becomes
active and takes over the cell’s functions as the active virus. After an active
period the virus once again hides until it becomes active again.
Viral Diseases
Cold, flu, cold sore are caused by a virus. Measles, chicken Pox, Polio,
Rabies, AIDS are all viral diseases.
Viral diseases spread in many of the same ways as the bacterial infectious
disease. Unfortunately there are no medications that can cure viral
infections. Over the counter medications are available to treat the symptoms.
To prevent infectious diseases vaccines are available. Vaccine is a substance
that stimulates the body to produce chemicals that destroy viruses and
Bacteria. (Antibiotics on the other hand work only against
infectious disease caused by Bacteria.)
Questions
1: Describe the basic structure of Viruses and explain their roles.
2: A space probe finds no sign of life on another planet. Is it likely that there
are viruses on that planet? Explain your reasoning.
3: Some people believe that taking antibiotics will help them recover more
quickly when they have the Flu. Explain what is wrong with the reasoning.
4: What does the virus need energy for?
5:Why are Viruses considered non- living?