The desired criteria in a molecule that can act as genetic material are as follows:
- It should have the capability of replication.
- It should be chemically and structurally stable.
- It should be able to incorporate slow changes (mutation) which are required for evolution.
- It should be able to express itself in the form of Mendelian characters.
Biochemistry of DNA and RNA:
- Both DNA and RNA show complementarity of base pairs and hence are capable of replication.
- As shown by Griffith's experiment, DNA is more stable than RNA because it can survive even heat-killing during the experiment.
- 2'-011 group is present in RNA. This makes RNA labile and degradable, which is not the case with DNA.
- Both RNA and DNA can carry on mutations. But DNA being more stable is better suited for the long-term storage of mutations.
Hence, DNA was preferred as the genetic material during evolution.
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