has just given NASA announced that its astrobiology department the bacterium with the terrestrial Name GFAJ-1 has discovered, which was the first known organism's biochemistry in the element phosphorus is replaced by arsenic.
This exotic micro-organism was found in Mono Lake in California. This is a lake that is three times saltier than seawater and which has high arsenic concentrations.
Previously it was thought that all life on Earth was always composed of carbon, nitrogen, sulfur, hydrogen, oxygen and phosphorus, the six blocks of living matter. The biomolecules of all organisms consist of most of these six elements. But now it has been found that one of these essential elements can be replaced by arsenic.
This has enormous implications for our understanding of life here on Earth and other planets.
The experiment
quite some time, some scientists have speculated about the substitution of phosphorus by arsenic. They decided to test this hypothesis, and conducted the following experiment.
you created a selective nutrient medium which contained no phosphorus contained, but high concentrations of arsenic. They added a sample from the Mono Lake and see if certain microorganisms still could live. Normally, in this hostile broth can survive anything, but this particular bacterium called GFAJ-1 not only survived, but began to grow even higher.
The phosphorus-free, arsenic-rich environment of the experiment was therefore ideal for GFAJ-1, as it had for any other life form lethal effects. Due to this hurdle (the lack of phosphorus) could allow scientists to exclude all others micro-organisms and unattractive feed selectively (selective) feeding ourselves up with the medium by microorganisms such as arsenic-based GFAJ-1, and grow.
phosphorus and arsenic
phosphorus is a limiting factor for all life because it is one of the six essential building materials for the traditional form of terrestrial life. ATP (power broker), DNA (carrier of genetic information), NADH (electron transport molecule) and many other biomolecules are phosphor. All life is therefore dependent on phosphorus - without phosphorus is the most we do not known life possible. Industrially useful phosphorus is a scarce commodity on this planet, because it can be promoted worldwide only a few places and it is the foundation of the modern food supply as a component of fertilizers.
arsenic behaves chemically similar to phosphorus, since it has the same number of electrons in the valence shell. This is made clear that phosphorus and arsenic in the periodic table in the same main group are (among themselves). Just as arsenic, phosphorus may enter into with its five valence bond similar situations, so that these two atoms can be replaced easily with one another.
This principle of chemical similarity, based on similar electron distributions in the outermost shell left, early researchers to speculate if there was not life based on silicon, which has instead of carbon as the most common element silicon. The substitution of carbon by Sililzium has been not found. But it could now prove at least that another of the six major building blocks of life can be replaced - and thus the equivalent principle for the essential building blocks of life is a fact.
of the specificity of GFAJ-1
What is so special about GFAJ-1? It is the first documented life form to use at all biomolecules instead of phosphorus arsenic. His DNA, are ATP and all the other important molecules are thus built up completely different than the previously known life on this earth.
date was not known DNA that would be just as stable and functional with arsenic instead of phosphorus, such as the already-known original. What are the chemical characteristics and new biological properties resulting from this substitution? Influenced the reading of the replacement of the genes? It gives the body new opportunities? As it can cope with the toxicity of arsenic? These organisms can be used for new disruptive technologies such as wastewater treatment or Phosphorrecyclierung?
It is as if we are first confronted with shirts made of synthetical fibers that make our recent clothing made of cotton and wool fibers completely in the shade and attract new, ingenious features.
is demonstrated in this video how the orange phosphorus atoms are replaced in the models of DNA, the NADH and ATP by green arsenic atoms, then represent that they are completely new biomolecules from GFAJ-1:
consequences
The detection of GFAJ-1 throws a fascinating new light on the versatile and highly adaptable life. Although it is still propagated is a terrestrial organism, but he shows us that huge difference, even right at our doorstep on discovery yet waiting.
Just as societies, are all living microorganisms and external (scientific writable) subject to constraints, which dictate the scope of societies and which creatures and they adapt and overcome with a little luck they may even. While all other bacteria die, it creates GFAJ-1 to survive in an environment free of phosphorus. It's like watching a company here when they first built a working aircraft and taken to heaven for mankind.
pull as far-reaching consequence of this finding must be well aware that it is not the atomic identity the building blocks of life, which make them essential, but their number bonds to which they are capable and general chemical behavior. Obviously, elements with similar bonding properties and similar chemical properties can be exchanged almost at will in life, if the environmental conditions forced by natural selection, the organisms in a particular direction
Concretely. It is, in principle, no matter whether it is a phosphorus atom or an arsenic atom acts as both have almost identical chemical properties and can thus meet the requirements of life when the environment is the way of life compels.
So that one can almost expect that we will take in the vastness of the universe to life forms that use depends on the nature of their surroundings silicon instead of carbon instead of oxygen or selenium.
What kind of a fascinating world we live.
Mono Lake in California - the home of GFAJ-1
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