Phosophorous(P) is the backbone of DNA – right??

Earlier this week NASA made a rather ambiguous pre-announcement. They left plenty of room for rumor, as the only detail they were willing to give was that the announcement involved a major find in Astrobiology. Astrobiology is the study of life in extreme environments, space, and on other planets. Quickly the rumor started flying about what the announcement could possibly involve; was it completely overblown and actually not exciting, or had they really found E.T.?

While the announcement itself did not involve a finding of life outside of Earth’s atmosphere, what was found was possibly the next most interesting find that could have been announced.

D.N.A. is a molecule necessary to carry out all the instructions for the development of an organism, whether that might be a protozoa, bacterium, insect, plant, or human. It is composed of five main chemicals one of which, phosphorous (P), creates the backbone of a DNA molecule phosphate. Without this background, the molecule could not be held together.

For a long time biologists have believed that phosphorous was the only such element that could bind together the DNA molecule. It was taught that without this element, life itself could not have arose, and therefore could not exist. NASA’s announcement has shed a new light on the subject, illuminating previously known corners of astrobiology.

The find comes from Felisa Wolfe-Simon and her team’s research at Mono Lake in California. Mono Lake is extremely arsenic(As) rich and shouldn’t support any form of life, as arsenic is extremely poisonous to life on earth, or at least that what biologists previously thought. The find that Felisa’s team discovered is that the lake actually does support life, but FAR from what we thought life was supposed to consist of, Carbon(C), Oxygen(O), Hydrogen(H), Nitrogen(N) and Phosphorus.

While the main four Carbon, Oxygen, Hydrogen, and Nitrogen were found in microbial life that her team found, the phosphate backbone had been replaced by an arsenate backbone. Arsenic itself is only one floor below Phosphorous on the periodic table, which means that the element itself is actually extremely similar.

The microbe itself, dubbed GFAJ-1, was developed in a laboratory, where it sat in an arsenic mixture as it grew for months. Overtime, the microbe replaced it’s sugar phosphate backbone with the newly discovered arsenic backbone, redefining what textbooks have up to this point instructed as the primary element needed to bind together the DNA molecule. It’s unknown at this point whether any other changes occured in the DNA molecule, but I would venture to guess there must be. Even so, it’d come as no surprise to me if not, and even if there was or wasn’t a major change to the DNA aside from the arsenate backbone, the ramifications of this find point to a major paradigm shift in biology.

A paradigm shift is when a new find presents information that completely revolutionizes previously known information. For instance, the heliocentric model (sun centered) that showed the earth revolved around the sun rather than the sun and planets around earth, or the Quantum Revolution in physics. Biology up to this point was thought to center around this one model of DNA, and it was believed that if life existed elsewhere in the universe that it would consist of roughly the same ingriendients. This belief has now been thrown upside down with Felisa’s discovery.

So what does this mean for the future of Biology and Astrobiology? This suggests that life as we know it on earth, our commonplace assumption that life must have a DNA molecule with a Phosphorous backbone, is wrong and that life can exist with a completely different “binding” on their book of instructions. However, does it stop with the phosphate backbone? Perhaps. However, part of scientific discovery that makes it so wonderful is finding things that you thought were true turned out to be wrong or at the least misleading. Perhaps there are creatures that are not Carbon based, but use some other element. Maybe on another planet somewhere orbiting a distant star, possibly another galaxy, there exists Nitrogen based organisms, in which case it’s a good thing David Duchovny is still alive.

“Break out the Head and Shoulders!”

While most people are rather disappointed in this find from Felisa and her team, I myself find it pretty exhilarating to knowlife can take different forms on the molecular level than we previously believed. It could mean that life could develop on planets that we before though was impossible to harbor life. While GFAJ-1 may have been a terrestrial organism, it represents the idea that life can develop in not only harsh or extreme environments, but completely toxic and deadly ones.

Survival it seems is not limited only to proper conditions and temperature, but has a wide array of methods to which it can adapt. It’s going to be interesting to see this implemented in the future, and where this takes scientific discovery.

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