The Viruses

The term "Virus", (poison in Latin) was coined in 1897 when a Dutch bacteriologist Martinus Beijerinck, passed the juice of a diseased plant of tobacco plant through a sufficiently fine filter as to stop the bacteria, still the pettiest. The clearing liquid filtrate, an infectious invisible agent still contained able to cause the illness of the tobacco plant called "mosaic" that Beijerinck was studying. In the following years, it was found that the viruses were related with a growing number of illnesses of the human beings and the animals. But it was not but up to 1931 in that the English bacteriologist William J. Elford devised a filter the sufficiently petty thing as to catch it in that was demonstrated that the virus was a minuscule particle, of much pettier size that the pettiest cell.

The viruses are so petty that twenty-five million polio virus would fit in the head of an alfilaria - as the virus that produces the aphthous one - they can be formed for only some few molecules.

The viruses are the most primitive forms in life, depending on the definition of "life" that you prefer. They can grow and to reproduce, but they are too petty to contain the usual machinery of a living cell.

In their place, they reproduce invading cells and forcing the chemical complex machinery from these when forming more virus instead of the main substances. In fact, most of a virus - a wraparound protein protector - he/she peels off and it is outside of the cell before beginning the attack. The part of the virus that invades to the cell is a mere matter tiny piece, a molecule or two of nucleic acid, the same substance that the genes are made.

The same as the genes, the viruses can supervise the manufacturing capacity of the living cell. But the virus is kind of a pirate" "gene that takes possession of the cell for its own ends. It carries out their protein masquerading as a genetic element of the own cell. Outside of their alive guests, the viruses cannot carry out metabolic features, to move neither to reproduce.

But inside the cell, a virus can arm hundred of replies of itself with the free nucleotides that float in the cellular liquid. When the cell is overworked, these replies abort the dead wraparound, transforming each one into a new "attacker" in search of other cells. Depending on the virus and of the victim, this cellular injury it is manifested as any other illness of a long list of them that you/they affect animals, plants or human beings, and that it includes mumps, measles, polio, hydrophobia, pock, influenza and the common cold. From 1911, when Dr. Peyton Rous sampled that a form of tumor of the chickens was caused by a virus, he/she has been that these cause more than 70 types of tumors in the animals.