HOW DID LIFE START?

28/02/2013

BIOCHEMISTRY

HOW DID LIFE START?

How did life start on planet Earth?

How did a ball made mostly of iron floating through space come to have self-replicating, self-aware organisms on it?

This is perhaps one of the greatest questions ever to be asked of science.  

There are many answers to this question that have been put forward in history. These answers have ranged in opinion from totally theological arguments on the nature of reality, down to the constructed logic of philosophical argument. 

However, where does science truly stand on this question?

We can build information processing technology that can transmit information to the other side of the planet at the speed of light, we can build space faring ships capable of placing men and machines on other worlds, we can develop instruments of such power and accuracy that we can study particles in thousands of times of magnitude smaller than our own eyes… yet where do we stand on this?

The embarrassing truth for science is that we truly have no idea.

The biological sciences are split along lines of what could ‘possibly’ have happened.

We are still learning the laws of biology and how the whole is greater than the sum of so many small parts.

Yet there are some strong arguments that are being put forward.

Cell membranes are especially interesting to this argument because they have an interesting quality. 

The membranes of cells are made up of billions of special molecules that are both hydrophilic and hydrophobic. This means that these long heavy molecules have one half of them that is attracted to water (like sugar that dissolves), and another half which pushed water away (like an oil or a soap).

Because of this, if they are dropped into a bucket of water they bind together. The part that’s trying to get away from water groups together and the parts that are trying to get close to it, binds in what is known as a polar bind.

After a while this process forms a thin layer. This layer is what all cells are made up of. Even if you blended the molecules completely up, they would still self-assemble into this shape.

THIS IS AMAZING!

So, if in the primordial earth these molecules are naturally self-assembling into membranes, there is the potential for them to enclose around other large and complex molecules that would also have the potential to be self-replicating.

Thus kicking off the self-replicating cells of the first simple organisms.

Some serious clout has been put behind this idea in the last few years as scientists compare the molecular makeup of the really large proteins that perform so many important cellular roles in your body.

These proteins are almost always based on very heavy metals such as Iron or Zinc. 

In the primordial earth the early ocean was covered in a layer of volcanic rock. Volcanic rock is naturally very porous (round air bubbles in it from cooled lava) and rich in these heavy elements.

It is just possible, that thanks to the presence of these porous rocks loaded with heavy metals that the membrane molecules were able to encircle around an extremely complex series of molecules using iron as a base.

Basically that’s the best scenario science has to offer,

That billions of years ago a volcano exploded and spewed lava into the complex molecule laden ocean which cooled with air bubbles in in that allowed the development of a membrane that protected another compound long enough for it to absorb enough energy to self-replicate.

Wow…

Problem with this is…

This completely ignores that fact that our best models for how these complex molecules form just create a global soup of extremely long hydrocarbons,

Or, that scientists have repeatedly attempted to duplicate these exact conditions in the laboratory and have never reproduced anything that would be considered a complex compound let alone something that was alive.

The correct answer is that, “we got no idea; we got a lot of figurin’ to do yet…”