Science Tuesday: What is a virus anyway?

As you may have observed, I like to step back sometimes and think about deep stuff. The origin of life is one of the Big, Hard Questions but a related question to which we have no clear answer is the origin of the viruses.Here ' s a good summary of the problem from Nature magazine.Most people begin by asking whether viruses are even alive. I classify that as a semantic quibble. Personally, I find the word " life " useful to describe self-replicating entities that expend energy for the purpose (and whatever else it takes along the way). Can viruses be said to satisfy those criterion? They replicate but they require the machinery of a living cell to do so. On the other hand living cells have certain requirements of their own. Similarly viruses don ' t expend energy on their own, they take over cells that then invest energy in making more viruses. Viruses really consist of an informational medium that takes over cells. The computer virus analogy is actually pretty good. Viruses are like malware. Malware is not a computer, so viruses are not life forms. But you can say whatever you like.So there are these bits of genetic material floating around, inside a protective protein package (often with other attached molecules). Cell walls incorporate what are called " receptors, " gateways that selectively let molecules in and out. Viruses are configured to get into cells through particular receptors (which is why they preferentially infect particular kinds of cells and thereby cause dif...
Source: Stayin' Alive - Category: American Health Source Type: blogs