At the moment, we’ve only got one viable blueprint for life: carbon-based and water dependent because that’s how life presents itself on Earth. This is why astronomers have directed their efforts into searching for exoplanets similar to our own. But that’s just vain because life could potentially thrive in other environments. It would only need to be made up of different elements.
Living cells need to be sheltered against their environment and the structure that achieves that is their membrane. A cell’s membrane is made up of two layers of phospholipids that act as a barrier, keeping useful stuff in and dangerous stuff out and for organisms on Earth, water is essential in the creation of the phospholipid bilayer. But that’s just one of the potential designs.
Recently, a team of Cornell astronomers and chemical engineers have come up with a model for a methane-based, oxygen-free cell membrane that could potentially run its processes in an alien environment. Yep, we’re going back to Titan!
Its seas of liquid methane would instantly freeze any water-based life form. But if cells were based on methane instead of water, they might just make the cut. The Cornell researchers proposed a cell membrane called an “azotosome” – a “nitrogen body” based on atoms of nitrogen, hydrogen and carbon, all of which are known to exist on Titan.
Their computer model showed the same elasticity and stability as the phospholipid bilayer while also being able to function at minus 290 degrees.
The scientists sifted through the compounds available on Titan and they found a possible candidate in the form of acrylonitrile, a substance commonly used in the production of acrylic fibers and plastics. While this organic compound is poisonous for Earth-based life forms, an acrylonitrile azotosome would have qualities similar to those of the liposome. It would be just as strong, flexible and durable in a methane environment as a liposome in water.
We’re not biologists, and we’re not astronomers, but we had the right tools. Perhaps it helped, because we didn’t come in with any preconceptions about what should be in a membrane and what shouldn’t. We just worked with the compounds that we knew were there and asked, ‘If this was your palette, what can you make out of that?'” – Cornell chemical molecular dynamics expert Paulette Clancy
Hell yeah, the only way science should be done is without prejudice!
The next step would be to see how azotosomes would fare in a methane-based environment. I bet you’re just as curious as I am to see what type of metabolism such a cell would employ. And most importantly, how would it reproduce in temperatures almost as cold as a witch’s tit in liquid nitrogen? For me, that has always been an impediment, but what do I know, I’m just a weak carbon-based, water-guzzling life form.
At the moment, this is all in the realm of speculation. Future missions to Titan and the likes will prove whether life is much more prolific than we thought. Wouldn’t that be something?