Life is built with three major components: RNA and DNA – the genetic code – and proteins, the cells that carry out their instructions. Most likely, the first cells had all three pieces.
But first, RNA, DNA or proteins had to form without their partners. One common theory, known as the “RNA World” hypothesis, proposes that because RNA, unlike DNA, can self-replicate, that molecule may have come first. Some scientists believe the process of its formation may not have been such a straightforward path.
In a paper published in the Journal of the American Chemical Society, Szostak Kim and colleagues present a new model for how RNA could have emerged. Instead of a clean path, he and his team propose a Frankenstein-like beginning, with RNA growing out of a mixture of nucleotides with similar chemical structures: arabino- deoxy- and ribonucleotides (ANA, DNA, and RNA).
In the Earth’s chemical melting pot, it is unlikely that a perfect version of RNA formed automatically. It is far more likely that many versions of nucleotides merged to form patchwork molecules with bits of both modern RNA and DNA, as well as largely defunct genetic molecules, such as ANA. These chimeras may have been the first steps toward today’s RNA and DNA.
But if these ‘Frankenstein’ molecules came first, why did they evolve to homogeneous RNA? To test the idea, scientists pitted potential primordial hybrids against modern RNA, manually copying the chimeras to imitate the process of RNA replication. Pure RNA, they found, is just better (more efficient, more precise, faster) than its heterogeneous counterparts are. In another surprising discovery, Kim found that the chimeric oligonucleotides – like ANA and DNA – could have helped RNA evolve the ability to copy itself. (1)
Meet life.
Highly disorganized. Highly chaotic. Highly volatile.
Resulting in robust designs.
Creating lasting bonds.
Setting the foundations of everything.
Meet death.
Highly organized. Highly structured. Highly stable.
Resulting in the chaos of death.
Creating nothing.
Setting the foundations of nothing.
Meet the world.
Woven out of thin thread. Balancing between life and death.
Neither living, nor dead.
Dead and living as well.
Can the fish exist without the sea?
– Hi.
– Did you have breakfast?
– No, there were no fish…
Explanatory Notes
- The “fish without the sea” is a mention to the idea that for something to exist, it may need a medium which has nothing to do with that something. The fish do not need fish to exist, they need the sea.
- Breakfast is a reference to Jesus last meeting with the Apostles.
