Expert: John Locke - 3/4/2008

Question
Hey, i would like to know the advantages and disadvatages of a virus to have either a RNA genome or a DNA genome

Answer
Thanks for using AllExperts, Pappu. There are two main points of comparison between RNA and DNA, as discussed below.

RNA is less stable as a molecule than DNA, meaning that it can be more easily damaged by environmental effects and thus rendered inoperable. DNA, having two strands and a slightly different chemical composition, is more stable and more easily repaired when damaged. It's this property that is believed to be the reason that DNA has flourished as the basis of the genetic code, while RNA has a smaller role for most organisms. DNA has the advantage in this fashion.

RNA can directly catalyze biological processes--that is, RNA can physically act like an enzyme in addition to coding for protein manufacture. DNA is incapable of doing this; DNA only serves as a blueprint for making RNA and proteins. Thus DNA viruses require more sophisticated cellular machinery to accomplish replication, while RNA viruses can do some of that work themselves. In this case, RNA seems to have the advantage.

RNA is generally considered more "primitive" than DNA, and accordingly RNA viruses are generally older than DNA viruses. They're usually chemically simpler as well, since RNA can't support some of the more complex aspects of DNA viruses.