Virus The Papillomavirus is a DNA virus that causes warts. These infectious particles are small, about 15 nm in diameter The Adenovirus is a DNA virus that causes colds and "pink eye".

Viral diseases in humans AIDSimmune system Chicken poxskin Common coldRespiratory system Influenzarespiratory system Measlesskin MumpsSalivary Tissue PolioNervous System

Definition A virus is a small infectious piece of material— much smaller than a fungus or bacterium—that must invade a living cell to reproduce (replicate). A virus is a small infectious piece of material— much smaller than a fungus or bacterium—that must invade a living cell to reproduce (replicate).

Adenovirus

The polio virus, left, once crippled millions. Courtesy of the MicrobeLibrary.org; © Jean-Yves Sgro, University of Wisconsin. The T4 bacteriophage, middle, is a virus that invades bacterial cells. Courtesy of the MicrobeLibrary.org; © Dennis Kunkel. Gold clusters bound to the knob protein of Adenovirus, right. Courtesy of Brookhaven National Laboratory.polio virusT4 bacteriophage

Virus Basics not living but contain genetic material not living but contain genetic material lack all cell structures lack all cell structures can reproduce ONLY in living cells and do not carry out any other life processes. can reproduce ONLY in living cells and do not carry out any other life processes. they survive by using the cell’s “machinery” to reproduce they survive by using the cell’s “machinery” to reproduce

More basics the Latin word for poison is virus the Latin word for poison is virus 1892 a Russian biologist discovered the first virus (a plant virus) 1892 a Russian biologist discovered the first virus (a plant virus) has genetic material (DNA or RNA) wrapped in a protein coat has genetic material (DNA or RNA) wrapped in a protein coat tobacco mosaic virus

What is a bacteriophage? It is a bacteria “eater” It is a bacteria “eater” Since the invention of the electron microscope, it is known as a virus. Since the invention of the electron microscope, it is known as a virus.

Size of common viruses NameSize Cowpox and smallpox 250 nm Influenza, mumps 100 nm Tobacco mosaic virus 65 nm Yellow fever virus 22 nm Polio 12 nm

Nanometer to meter {scientific notation} SizeConversion 250 nm 250 x nm x nm x nm x nm x 10 -9

How do viruses infect cells ? The virus takes control of the cell machinery The virus takes control of the cell machinery The cell “forgets” its own needs and works for the benefit of the virus. The cell “forgets” its own needs and works for the benefit of the virus. There are 4 steps to how a virus replicates itself once it attaches to a cell : There are 4 steps to how a virus replicates itself once it attaches to a cell :

More on Active Viruses Attach a specific virus attaches to the surface of specific bacterial cell. Invade The genetic material of the virus is injected into the host cell Copy The nucleus of the host cell begins copying the genetic material of the virus Release The cell bursts and a lot of new viruses are released. The new virus cells go on to infect other cells.