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 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… How Viruses Work Video (2:25)

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 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.

Symptoms ColdFlu FeverRare Characteristically, high ( o F) Cough, Chest Discomfort Hacking Nonproductive, common; can become severe HeadacheRareProminent General Aches, Pains Slight Usual; often severe Fatigue, Weakness Very mild Can last up to weeks Extreme Exhaustion Never Early and prominent Stuffy noseCommonSometimes SneezingUsualSometimes Sore ThroatCommonSometimes Cold vs. Flu How to know what you have.

Herpes