Transcript Viruses! - nimitz163

Viruses!
What are Viruses
VIDEO (3:35)
It did not take doctors long to find out that the
medicines that are usually used to fight bacterial
diseases did not work on all illnesses.
They figured that something other than bacteria and
protists must be causing diseases in humans as well.
This led to the discovery of viruses.
Viruses are
microscopic
particles that
invade the cells of
plant, animals,
fungi, and
bacteria. Viruses
often destroy the
cells they invade.
AIDS Virus
A virus is not a cell. A typical virus is composed of a
core of genetic material surrounded by a protein coat.
The protein coat protects the virus and enables it to
invade its host cell.
In many viruses, DNA is
the genetic material.
Other viruses have RNA.
Viruses are parasitic and
can reproduce only inside
the cells of their host.
This makes viruses very
different from bacteria
and protists.
Viral genetic material has room for only a few genes. Usually
they are only genes that code for the protein coat and for
enzymes that enable to virus to take over the cell.
There has been an ongoing debate among scientists as
to whether or not viruses are alive or not alive. Viruses
lack three essential features of living things:
1. They are not made of cells
2. They cannot make proteins by themselves
3. They cannot use energy
Even though viruses can
reproduce they are only able to
so when inside living cells.
Because they cannot reproduce
on their own most scientists
classify them as non - living
things.
Virus Reproduction
How Viruses Work Video
(2:25)
All viruses reproduce by taking over the reproductive
machinery of a cell.
The following is a story to help you visualize what
it is like for a virus to reproduce…
Once upon a time there was a factory
that made cars and trucks.
Everyone who worked in the factory
was very happy making cars and trucks.
One day a crazy man came
to the factory with an army
tank! He told all the workers
in the factory that they would
not be allowed to make cars
and trucks anymore.
They were only allowed to
make tanks! The crazy man
had the blue prints for the
tanks and he forced the
workers in the factory to
make tanks instead of cars
and trucks.
Once the crazy man had enough tanks he would
send them out to find and take over other factories
and make them produce tanks too.
In the story the virus is represented by the crazy
man in the tank. The virus takes over the healthy
cell (like the tank took over the factory) and force
the cell to make viruses instead of making other
cells. Once the cell is full of new viruses it bursts
open and all the new viruses take over new
healthy cells.
Our mainline of
defense against
viruses are the white
blood cells in our
bloodstream.
These white blood
cells seek out viruses
and attack them.
Killing them as quickly
as possible before
they can take over
other cells.
Some Infection-Fighting
White Blood Cells
Vaccines Video
(3:22)
The illustration is an electron
micrograph of a mixture of
erythrocytes (red blood cells)
and leucocytes (white blood
cells) The erythrocytes are
the flattened, donut-shaped
cells. They lack nuclei and
possess millions of
hemoglobin molecules
whose function is to
transport oxygen throughout
the body. The leucocytes
(white blood cells) are the
round cells with a spiked
appearance. They function to
identify and remove foreign
proteins (bacteria, viruses,
toxins, etc.) from the body.
This is the body's main
disease fighting mechanism.
This is an actual picture of White Blood Cells, in with some red
blood cells. The platelets are stained purple, a T-Lymphocyte
white cell is stained green, and a Monocyte white cell is stained
gold as seen through a scanning electron microscope.
The reason HIV is such a dangerous virus is
because it has the ability to take over the white
blood cells!
HIV waits for a white blood cell to attack it, then
it takes over the white blood cell and makes it
into a virus making factory.
The effect of this is
that other viruses
can now take over
your body and kill
you because your
defenses have been
taken down by the
HIV.
Viruses cause serious human diseases in addition to AIDS,
such as measles and influenza.
Viral diseases are much more difficult to treat than
bacterial diseases. This is true for a few reasons.
#1 most antibiotics that are used on bacteria disrupt the
bacteria’s cell wall or proteins inside the bacteria.
Since a virus has no cell wall or inner proteins it is immune
to those medicines.
#2 since viruses actually enter healthy cells,
it is hard to find them.
Not only is it difficult to find them but it is hard to kill them
without also killing the cells they are living in.
The most effect defenses we have
against viral diseases is
vaccination.
When you receive a vaccination
your body is able to ‘learn’ how to
find the virus and then if you ever
catch it your body will know how
to kill it.
Vaccines have helped wipe out diseases like small pox
that used to kill millions of people every year.
However, vaccines are not available for all viruses.
There are many viruses that we do not have any defense
against and even if we do sometimes the viruses will
mutate which can make the vaccine ineffective.
Cold vs. Flu
How to know what you have.
Cold
Flu
Rare
Characteristically,
high (102-104oF)
Cough,
Chest Discomfort
Hacking
Nonproductive,
common; can
become severe
Headache
Rare
Prominent
General Aches,
Pains
Slight
Usual; often
severe
Fatigue,
Weakness
Very mild
Can last up to 2 3 weeks
Extreme
Exhaustion
Never
Early and
prominent
Stuffy nose
Common
Sometimes
Sneezing
Usual
Sometimes
Sore Throat
Common
Sometimes
Symptoms
Fever
Herpes
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