Viruses are mysterious. They can survive almost any environment on earth and have the uncanny ability to duplicate themselves and exist for centuries. They do not need food, water, or even air to survive. Even though we know so much about viruses, we still have a lot of learning to do to uncover all of their mysteries.
Viruses are formed from just a few chemicals. A thin layer of protein protects their DNA or RNA core. DNA and RNA are molecules that carry the genetic code that instructs the virus to make an almost exact copy of itself. But the virus cannot do it all alone, it must go into a host cell to make replicas of itself. Some viruses need plant host cells. Others need animal, human, or bacteria host cells.
Viruses come in different shapes and sizes: rounded, sharp, tiny and big. For example, a measles virus is filled with spikes. Some pneumonia viruses are round and are constructed of twenty triangles attached edge to edge.
The bacteriophage, also known as the bacterium eater, is a virus that attaches to a bacterium. It has a six-sided head with a spiraled tail with six spindly fibers sticking out the end. The virus' tail makes a hole in the bacteria, and inserts its DNA payload. Eventually, there are so many new viruses inside that the cell wall explodes, and the bacteriophage goes in search of more bacteria, and repeats the process.
Viruses are fascinating things. They have many abilities that we don’t have. They may be tiny, but they can be very deadly. Still, we have much to learn about them.
[Source: Bill Nye the Science Guy: Great Big Book of Tiny Germs]