Question: if viruses are nonliving how are they able to take over another cell

Stephanie Moon answered on 27 Apr 2016:

Hi kklol303!
I like this video because it shows some cartoons of what happens when some kinds of viruses infect a cell http://www.hhmi.org/biointeractive/viral-lifecycle . Basically, viruses are like really simple, tiny cells. They are made of the same types of things that cells are made of- protein, sometimes fats, and DNA or RNA. But since their genomes are so small- we have billions of base pairs of DNA but many viruses only have 10-100 thousand base pairs– they don’t have enough space to encode all of the molecular machines (mostly proteins) to allow them to divide by themselves. So they have to get into a big, complicated cell that has all of these molecular machines available (for the cell to use) and take over that machinery to replicate. There’s a debate about whether or not viruses are alive- because there is no one simple way to define ‘life’. But they can’t divide on their own, so for a lot of scientists that is enough to define them as non-living.