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Science!

It has to be self-replication – making a copy of yourself (See Fig 2). Once you make copies of yourself, your population can grow and expand. Can DNA do it? Many would say yes. Many would be wrong. DNA can’t do shit. Its job is to store information. It has to be as inert as a dusty old tome in the darkest corner of the Barr Smith. It sits in its ivory tower and tries its hardest to just not get involved. When it comes to cell replication, DNA has to be replicated, but it needs a lot of help from its entourage of proteins. RNA, on the other hand, is a much more likely candidate. It gets in there and gets its hands dirty. Sure, it can carry information, too. That’s what mRNA is for (See Fig 3). It also provides the key machinery in making proteins: transfer RNA (tRNA) and ribosomal RNA (rRNA). RNA can also manipulate other RNA. Spliceosomes (which contain snRNA) and ribozymes (RNA enzymes) use RNA to manipulate RNA. It doesn’t self-replicate though. But...maybe it could...maybe it used to. Some scientists certainly thought so. So they set out to make an RNA molecule which could make itself. In

April, Aniela Wochner and her co-workers* got as far as any has to date. Their baby, called tC19Z, is a record holder. The previous best self-replicator was R19, which can copy only 14 of its 196 nucleotide letters. tC19Z blows that out of the water at 95 of 198 nucleotides. These experiments provide tantalising hints at the origin of life. It seems possible that RNA was the first molecule of life; able to self-replicate and look after itself. Over time, RNA enlisted the help of proteins to do some work around the place, and put DNA to work in the library. So where does this leave DNA? It’s been demoted. No longer can DNA be seen as the master. For me, DNA is now simply the information repository. A dusty old tome. To be sure, that dusty tome tells the story of all life on Earth. It contains the magical, mystery, poetic history of our, and every other, species. But, RNA is really running the show. The King is dead, long live the Queen! O

*  Wochner, A et al (2010) Ribozyme-Catalyzed Transcription of an Active Ribozyme.Science 332 pg 209-212.

Volume 79, Issue 6

13

Profile for On Dit

On Dit Issue 79.6  

On Dit looks at tattoos, Pokémon and pubs, instructs you on how to become a crazy cat lady, gets its hands (and pretty much everything else)...

On Dit Issue 79.6  

On Dit looks at tattoos, Pokémon and pubs, instructs you on how to become a crazy cat lady, gets its hands (and pretty much everything else)...

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