Why RNA? Because when I look at a skyscraper, only rarely do I appreciate the envelope; more often, it’s the structural and mechanical engineering of the building that fascinates me.
Micelles are beautiful, and their self-assembly is undeniable. But to place them at the very beginnings of life ignores to many facts. Life, for billions of years, was prokaryotic—with one living thing a single sac filled with biochemistry. And, at the core and origins of biochemistry is RNA—capable of both replicating itself and performing enzymatic functions. When I look at living things, I frequently see beyond the structural beauty—to see the beauty inherent in the chemistry of life, the mechanical engineering of life.
So, Charles, I propose a compromise: RNA at the starts of life, the simple life that was all of life for billions of years. And lipids—the compartment after compartment that makes up the eukaryotic cell—as the origins of complex life. Without the ability of lipids to segment space—to create specialized rooms for chemistry to occur—living things would never achieve the complex and rich world we live in.
Whoa there, Jonathan. Fix all your typos and then we’ll pick up this debate.
Oh, come on, don’t even give him that. (Phospho)ipids may be crucial for complex life, but that still doesn’t make them the origin in any meaningful way. They can’t transmit information.
I could even dream up a story about cells learning to create semipermeable membranes in some other way, sans fatty acids. Some sort or properly polarized protein business. The phosopholipid bilayer is undeniably more elegant, but sometimes biology is inelegant and still functional. But without RNA? I got nothin’.
You got nothin’? Anything repeating in a pattern, anything potentially replicable…
And don’t prokaryotes have a lipid membrane?
Protocells required both replicating material inside, and a lipid membrane to hold crap together to really become replicators.
Remember, evolution is not selecting for transmission of information, per se. It’s only selecting for replicability.
This is why I love SLOG. I request more bizarre Mudede/Golob ruminations.
Why lipids and not polysaccharides (particularly cellulose), which give plant cells their structure? What makes this molecule so special?
As someone who studies RNA semi-professionally (i.e. as a grad student), I concur. RNA 4 Life, yo!
I barely understand either of you, but this Mudede/Golob exchange was the best thing on Slog in a week.
Agreed. More metaphysical/biochemical conversations, please!
There’s nothing metaphysical about this discussion. But Chuck should definitely stick with poetry cuz every time he ventures into the scientific realm, he fucks it up.
But Jonathan, I’m not entirely convinced that RNA can “replicate” itself. It can serve as a template to situate two things near each other and then perform its enzymatic function, but I’m not sure that’s really “replication”. If I understood Joyce’s paper (and correct me if I’m wrong), the “building blocks” they used were half the size of the template/self-replicating RNA and the RNA needed to make only one linkage to get the new molecule. I must be wrong, because I don’t understand why everyone else would consider that replication.
No, RNA is capable of replicating just like DNA is by using itself as a template. That kind of RNA would be message RNA or mRNA. But there are other RNA molecules that do other things, like transfer RNAs which bring nucleic acids to the template strand of mRNA (or in our case our DNA) to make copies. To be an RNA organism isn’t half bad. There’s lots of wildly successful RNA viruses that consist of their RNAs, a protein coat, and maybe a handful of their own proteins. Everything else they may need they can take over in the infected cell or build for themselves using the cell’s machinery.
Is it possible nucleic acids are made in super novas?
Give me a bit of miRNA and a side order of siRNA to twiddle the bits and I’ll make you a really complicated picture from the same slices of DNA.
I’m surprised it took 13 whole posts before Will managed to work twiddling his bits into the thread.