#9: Viruses

Viruses are not true living things. They are not considered to be alive, because on their own they can do nothing until they enter a living cell.










Viruses are complicated assemblies of molecules including proteins, nucleic acids, lipids, carbohydrates…

When viruses encounter a cell, they take over cell’s machinery. A series of chemical reactions occur that lead to the production of new viruses. Theses new viruses burst out of the cell and invade others, where the process is repeated. The host cell is usually killed when this happens.

These steps are completely passive, that is, they are predefined by the nature of the molecules that comprise the virus particle. Viruses don’t actually ‘do’ anything. Without cells, viruses would not be able to multiply. 

Scientists do not classify a virus as a living thing. This is because:

• it does not show all seven processes for life
• when it enters a cell it changes the way a cell works so it can make copies of the virus.