Humanosity says…It’s one of life’s most enduring questions – Just how did life get started? What turned chemistry into biology? This article details the latest breakthrough which brings us closer to understanding how life may have originated.
Cells are what make up every living thing on the planet. All cells are made up of three basic elements. First of all, there is a membrane or sac which is made up of fatty acids. Then there are proteins which are like workhorses and perform a lot of the tasks that happen inside a cell. Finally, there is the DNA and it’s simpler cousin RNA which encode all the information for the cell to function and copy itself.
All these elements were probably present in the first protocell which preceded all life. Many scientists believe that the membrane or the bag which contained everything was crucial. On the primordial earth, all the molecules present in the water were free to move around. By confining them the membrane concentrated these molecules and forced them to interact with each other.
The amazing property of fatty acids is that one end of the molecule is drawn to water whilst the other end is repelled by water or is hydrophobic as the scientists say. Throw a bunch of fatty acid molecules in water and they will naturally assemble to form a sac with the hydrophobic tails of the molecules on the inside of the sac.
The Salt Problem
The fact that fatty acids automatically self assemble into cell membranes seemed very fortunate for life but there was a problem. Scientists believe life first arose in the salty oceans and salt catastrophically destabilizes the fatty-acid spheres. Also, certain ions, including magnesium and iron, cause the spheres to collapse, which is problematic since RNA—another key component of early protocells—requires these ions
This is where the latest breakthrough comes in. Researchers at the University of Washington were wondering just how the three elements of a cell would have interacted with each other. When they placed fatty acids in a medium with salt or the iron and magnesium ions the fatty acid spheres predictably collapsed. However when they introduced the protein element in the form of amino acids something amazing happened.
Amino acids are the building blocks of protein and have been found everywhere in the universe, from the early earth to comets and asteroids, even in the vast clouds of gas are the basis of star and solar system formation.
These amino acids prevented the fatty acid spheres from collapsing. It means that two of the essential components of life, a protocell’s membrane and its proteins, provided the conditions for each other to exist. By sticking to the fatty acids, the amino acids gave them stability. In turn, the fatty acids concentrated the amino acids, perhaps encouraging them to coalesce into proteins.
What’s more, the fatty acid spheres developed a second internal sphere and this is what all the cells that we are made of look like.
Early studies had only found interactions between two of the three key components of a cell. This latest research shows how all three elements naturally interact with each other and brings the protocell one step closer to making the leap from chemistry to biology.
Scientists are still debating whether or not life formed in shallow volcanic pools or in hydrothermal vents deep in the oceans. However, the joy of this latest breakthrough is that it works in both scenarios.
Sources: www.theatlantic.com, www.pnas.org, www.exploringorigins.org
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