So, last semester we had this Genetics course, and it was so interesting because we learnt so much (yes, I think learning is fun). There was this one topic about RNA and it got me thinking about how amazing RNA is. Let me explain...
We all know what DNA is (hopefully), and how important it is (genetic code, storing important information, making you human yadda yadda). But there is so much more to Genetics that we usually don't think about. Take Epigenetics for example: inheritance doesn't only depend on your nucleotide sequence (DNA). Even without changing the DNA sequence you can produce heritable changes. Heredity beyond DNA, how awesome is that? But that's alot of molecular biology I shouldn't get into...
Even from an evolutionary point of view RNA holds alot of importance. When we (biologists) say "the RNA world", we're mostly talking about this period of time when all life consisted of RNA and DNA had as yet not 'evolved'. How do we know RNA came before DNA? Well, there are alot of reasons but one major (Nobel Prize-winning) reason is that RNA has catalytic activity. So, a non-protein molecule acting as an enzyme, that's pretty cool, not to mention extremely useful.
The list of what RNA can do, and if-it-did-NOT-do-that-how-terrible-it-would-be is very long. Some of these things are:
1) Dosage Compensation - never thought that difference in the male and female genotype (XY and XX) could cause problems? With females having two copies of X, there would be double the gene product which would have disastrous effects. But RNA saves the day: one X chromosome inactivated.
2) There's also Gene Imprinting - a really complicated yet brilliant transmission of genetic characteristics that has nothing to do with your genetic make-up.
3) Also, 'how' you exist is controlled by RNA. If all of your genes were activated in all of your cells, you'd be a sorry excuse of a human being. So gene expression (which genes are expressed where - stuff that makes you function properly) is regulated by RNA and Epigenetics.
All of these RNA molecules (non-coding RNA) are not involved in general protein-synthesis pathway (transcription, translation). Recently an explosion in the number of these non-coding RNA's has been seen and they control remarkably diverse functions. In the end, I'll quote from the Review Article that was the inspiration behind this post: "Some have likened this period to an RNA revolution...it is perhaps more apt to call it an RNA 'revelation'. RNA is not taking over the cell - it has been in control all along. We just didn't realize it until now."