Why can't the messages be taken right from the RNA?

Answer 1

The reason that the instructions for creating proteins are stored as DNA, and not RNA is that RNA is much less stable than DNA. This means that if the information (or message) for how to create a protein was kept on RNA, it would soon degrade - and the instructions would be lost.

DNA is much more stable than RNA, and because it does not leave the nucleus (in eukaryotic cells) it is much less likely to be degraded. This is why the instructions for protein synthesis cannot originate with RNA.

DNA is more stable for many reasons, two of the simplest being; it is double-stranded (the hydrogen bonds in the centre provide stability) and it contains an H on its 2 position instead of an OH (less likely to be involved in reactions).

Answer 2

Messages cannot be directly taken from RNA because RNA is an intermediate molecule that carries genetic information from the DNA to the ribosomes, where proteins are synthesized. The information stored in DNA is transcribed into RNA, and then translated into proteins. Therefore, to obtain the complete genetic message, the information needs to be transcribed and translated into proteins.