One of the biggest unanswered questions in science today is, how did life begin on Earth? and it is the backbone of our burning questions about, who we are? where we come from? and if we’re alone out here. New research has now given us pieces of information into how precisely the key molecular building blocks of life came together in the first place.
How did the perfect ingredients for life form?
Now the central question – In the big pre-biotic earth, as in, earth before living organisms, how did the perfect ingredients for life form? substantially fuse together into something that stores data and can recreate autonomously. A primer on how our living cell’s work. A cell’s most important components are DNA, RNA and a ribosome. DNA codes for all of the essential information about what the organism is and how it works, but it’s kept all safe and huddled away in the nucleus.
To take that information and make it into actual stuff, like proteins, an enzyme called RNA polymerase copies sections of the DNA and makes strands of RNA, which are a like one-sided version of DNA. These messenger RNA strands get sent to the cell’s ribosome, where they are converted into the proteins our cells need for survival.
So, how it all started?
When scientists were first discovering all this complex stuff, it became an even bigger question of how all this could have spontaneously come together as a result of organic chemistry. To tackle this problem, some scientists suggested that perhaps life, as we know it now, didn’t all spontaneously form at once exactly as it is. It was probably a little simpler, maybe it was only RNA-based.
This hypothetical situation is what we refer to as the RNA world. But this track of thinking is based on the idea that the self-replicating aspect of life is what formed first. And not everyone agrees. Some people think that metabolization, or the ability to extract energy from your environment, must have come first, while a third camp thinks that compartmentalization must have come first, a primitive version of the different internal pieces of a cell.
These divisions in the scientific community still survive, but as we’ve come to learn more about RNA and how it can behave, it’s become clearer that it’s an essential part of the beginning of life, if not the first thing that formed. This is because RNA can do a really exciting thing. Not only can it contain information that it can then replicate, but it can also fold itself up into shapes in which it can act as an catalyst, influencing chemical reactions. When this was discovered, we realized it was much more likely that RNA-based life could indeed have survived and replicated all on its own, without the all the fancy add-ons we have today.
How did RNA form in the first place?
So, then we come down to the question again, how did RNA form in the first place? Well, Scientists have been on a quest to demonstrate how all of RNA’s component parts could have spontaneously assembled, and new research may just bring it all together. RNA is made up of the nucleic acids cytosine, uracil, adenine, and guanine. A research team had shown a few years ago that a set of five simple compounds could have given rise to cytosine and uracil with nothing more than the addition of UV light, which there was plenty of on a primitive earth.
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A different team then showed a similarly easy and plausible process for the formation of adenine and guanine from simple building block elements. But no one had demonstrated that these two separate reactions, producing all four RNA nucleic acids, could have occurred in the same place at the same time, until now. So, How did life begin on Earth?
A paper that came out in 2018 showed that a simple set of molecules i.e., oxygen, nitrogen, methane, ammonia, water, and hydrogen cyanide, all of which would have been present on an early version of earth, could react to form what we recognize as the uracil, adenine, guanine and cytosine. This work is the first experimental evidence showing that the chemistry fits. These building blocks could have feasibly all come together at the same time, in the same place, we saw it happen before our very eyes.
There are still a couple of missing pieces that we haven’t been able to recreate in the lab. For instance, how did each of the building blocks come together to link them into the long chains that take them from nucleic acids to actual RNA? And, keep in mind, while the RNA world is the leading theory, there is some contention among scientists about the first inklings of life on earth. Hopefully work like this will add to that discussion, plus it does represent an unprecedented step forward in answering the most fundamental of questions: How did life begin on Earth?