1. Chapter 7
Viruses

2. What is a virus? Characteristics of Viruses
Virus is a tiny, nonliving particle that invades and then multiplies inside a living cell
Viruses are not cells
They do not have the characteristics of organisms
They only way in which viruses are like organisms is that they can multiply
Host is a living thing that provides a source of energy for a virus or an organism
Parasites, are organisms that live on or in a host and cause it harm

3. What is a virus? The structure of Viruses
Viruses are smaller than cells and vary in size and shape (some are round, look like rods, bricks, etc.)
Bacteriophage is a virus that infects bacteria
The proteins on the surface of a virus play an important role during the invasion of a host cell
Each virus contains unique surface proteins
Lock-and-key
All viruses have two basic parts:
A protein coat that protects the virus
An inner core made of genetic material

4. How Viruses Multiply
Once inside a cell, a virus’s genetic material takes over many of the cells function. It instructs the cell to produce the virus’s proteins and genetic material. These proteins and genetic material then assemble into new viruses.

5. How Viruses Multiply Active Viruses
A virus attaches to the surface to a bacterium
The virus injects its genetic material into the bacterium
The virus’s genetic material takes over the cell functions of the bacterium. The cell starts to produce the virus’s proteins and genetic material
The proteins and genetic material assemble into new viruses that fill the bacterium.
The bacterium bursts open, releasing new viruses. The viruses go on to infect more cells

6. How Viruses Multiply Hidden Viruses
A virus attaches to the surface of a bacterium
The virus injects its genetic material into the bacterium
The virus’s genetic material becomes part of a genetic material of the bacterium
After some time, the virus’s genetic material removes itself and becomes active
The cell begins to produce the virus’s proteins and genetic material, which assemble into new viruses
The new viruses crowd the bacterium. Finally, the cell bursts open and releases the new viruses

7. Viruses & Disease The spread of viral diseases
Viral diseases can be spread in various ways
Example: some can be spread through the contact with a contaminated object, or through a bite of an infected animal
Cold’s an flu viruses can travel in tiny drops of moisture that an infected person sneezes or coughs into the air
Others can be spread only through contact with body fluids, such as blood

8. Viruses & Disease Treating Viral Diseases
There are NO cures for viral diseases
However, many over the counter medications can help relieve the symptoms
The best treatment of a viral infection is bed rest
Resting, drinking plenty of fluids, and eating a well balanced meal may be all you can do while you recover from a viral disease.

9. Viruses & Disease Preventing Viral Diseases
A vaccine is a substance introduced into the body to stimulate the production of chemicals that destroy specific disease causing viruses and organisms
A viral vaccine may be made from or altered, the viruses in the vaccine do no cause disease; instead they trigger the body’s natural defenses
Another important way to protect against viral disease is to keep your body healthy
Eat nutritious food
Get enough sleep, fluids, and exercise
Washing your hands
Not sharing eating or drinking utensils