Question

Researchers have proposed that early life on Earth used RNA as its source of genetic information and that DNA eventually replaced RNA as the source of genetic information. What aspects of DNA structure might make it better suited than RNA to be the genetic material?

Answer 1

With the exception of certain viruses, DNA rather than RNA carries the genetic information in all form of life on earth.DNA is both more resilient and more easily repaired than RNA.Both DNA and RNA contains the ribose sugar which is a ring of carbon atom surrounded by oxygen and hydrogen.But where RNA contains complete ribose sugar and DNA has an incomplete ring lacking an oxygen atom at 2nd carbon of the ring.This minor difference is responsible for the name also. But the major fact is that under alkaline condition, 2`OH group losses it's hydrogen and generate deprotomated hydroxyl group which attack On phosphodiester bond and causes hydrolysis of RNA. DNA doesn't undergo this kind of reaction and is much more stable than RNA.

In both DNA and RNA the base cytosine under go spontaneous deamaination and generate uracil. The uracil generated by deamination And the original is completely indistinguishable thus RNA can not be repaired while DNA contains thymine at the place of uracil thus making uracil easily detectable by the repair machinery and get repaired.

In double stranded DNA the bases are burried in the double strand protecting them from chemical mutagen and maintains the original information on DNA while in RNA  bases are freely exposed to react with chemical that gives rise mutation.

During DNA replication there are lot of mismatch.the mismatch in one strand can be repaired by taking the information from other strand but RNA can't be repaired in this way.

So above discussed point illustrates that DNA can serve as good genetic material over RNA.