In the latest episode of Genetics Unzipped, presenter Dr Kat Arney takes a trip back in a virtual time machine, soaking in the primordial soup to discover the origins of DNA, find out where genes come from and how some species have stolen theirs from viruses, and explore what’s next for the genetic code.
Unravelling the origins of DNA
Experts think that the first step towards life was simply a molecule that was capable of self-replicating.
As a geneticist, your mind might jump straight away to the most famous self-replicating molecule of them all, DNA. In fact, that’s probably the least likely scenario, but what actually happened is still a hot topic of debate among researchers searching for the origins of life.
Did life start off in an RNA-based world? Did DNA and RNA evolved together? Or are protein-first metabolic explanations more likely? We take a look at the ideas and the evidence to see which might have come first.
Where do genes come from?
Moving from DNA to genes, as far as we can tell, all of life on earth evolved from one common ancestor, LUCA, which must have had one set of genes, whatever they looked like.
But that still leaves open the question of how this simple set of genes diversified to encompass the incredible diversity of genes that now exist in trillions of extant and extinct species on earth. We look at where genes come from, and how we’ve managed to steal some from our mortal enemies, viruses.
For example, syncytin genes, which make proteins that help form the placenta during pregnancy and stop the mother’s immune system from attacking her baby in the womb look suspiciously like genes from a retrovirus – which are often masters at evading attack from the immune system.
Expanding the genetic alphabet
Finally, you may think you know your A, C, T and G when it comes to DNA, but what about B, P, S and Z? We discover how the genetic code is expanding, thanks to Hachimoji DNA.
The creation of Hachimoji DNA – along with Hachimoji RNA and enzymes capable of transcribing one from the other – demonstrates that the current canon of naturally-occurring nucleotides are not unique in their ability to store genetic information.
Could DNA-based life on other planets might use a different genetic code entirely? Or could a new and improved genetic code might evolve right here on earth in the next few billion years? Watch this space…
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Genetics Unzipped is the podcast from the UK Genetics Society, presented by award-winning science communicator Dr Kat Arney and produced by First Create the Media. Follow Genetics Unzipped on Twitter @geneticsunzip, and the Genetics Society at @GenSocUK