![]() ![]() ![]() Friedrich Miescher, a Swiss chemist working in Germany, was studying white blood cells (leukocytes). Scientists first began to investigate the unique chemical properties of DNA long before the structure of the molecule was understood, and even before DNA was discovered to be the genetic material. As we all know, living things do eventually age and deteriorate, much like the old house and rusty car, but by making copies of our DNA and passing it to our offspring, life continues. And it is the unique chemical properties of DNA that allow it to generate copies of itself. To do this, they must first copy their genetic material, their DNA (see our DNA I module for more information). This is because living things have a fascinating and somewhat unique ability to reproduce and make "copies" of themselves. Your children are no weaker or more likely to fall to pieces than you are. Yet, life on Earth continues to flourish. Most objects you are familiar with will eventually fall into ruin if not constantly maintained: a car will eventually rust and fall to pieces a house will spring leaks in the roof and fall to the ground even mountain ranges are eroded by wind and rain. Pair (noun) a set of two two similar things that form a unit two similar things that are used together pair (verb) to arrange in a set of two to become grouped together with one other similar thing strand a long, thin piece of something a length of something thin like string Visit for the latest in space science and exploration news on Twitter and on Facebook. 8 in the Proceedings of the National Academy of Sciences.įollow contributor Charles Q. "It is always exciting to find extraterrestrial and ancient 4.6 billion-year-old organic compounds that might have had a role in early life," Cooper added.Ĭleaves, Cooper and their colleagues detailed their findings in two studies published online Aug. "One function of this cycle is respiration, when organisms give off carbon dioxide." The citric acid cycle is "thought by many experts to be among the most ancient of biological processes," study co-author George Cooper, a chemist at NASA Ames Research Center, told. In a different study, researchers discovered molecules that make up key parts of a vital biological pathway, the citric acid cycle, in a number of carbonaceous chondrites. "Are these building blocks of life transferred to other places where they might be useful? Can alternative building blocks be used to build other things?" "All this has implications for the origins of life on Earth and potentially elsewhere," Callahan said. "At the start of this project, it looked like the nucleobases in these meteorites were terrestrial contamination - these results were a very big surprise for me," study co-author Michael Callahan, an analytical chemist and astrobiologist at NASA Goddard Space Flight Center, told. "Finding nucleobase compounds not typically found in Earth's biochemistry strongly supports an extraterrestrial origin," Cleaves said. Intriguingly, three of these nucleobase analogs are very rare in Earth biology, and were not found in soil and ice samples from the areas near where the meteorites were collected at the parts-per-billion limits of their detection techniques. Two of the carbonaceous chondrites contained a diverse array of nucleobases and structurally similar compounds known as nucleobase analogs. The analytical techniques probed the mass and other features of the molecules to identify the presence of extraterrestrial nucleobases and see that they apparently did not come from the surrounding area. This was the first time all but two of these meteorites had been analyzed for nucleobases. To help confirm if any nucleobases seen in meteorites were of extraterrestrial origin, scientists used the latest scientific analysis techniques on samples from a dozen meteorites - 11 organic-rich meteorites called carbonaceous chondrites and one ureilite, a very rare type of meteorite with a different chemical composition. "People have been finding nucleobases in meteorites for about 50 years now, and have been trying to figure out if they are of biological origin or not," study co-author Jim Cleaves, a chemist at the Carnegie Institution of Washington, told. However, it has been very difficult to prove that these molecules are not contamination from sources on Earth. Investigators have also found nucleobases, key ingredients of DNA, in meteorites before. Space rocks just like these may have been a vital source of the organic compounds that gave rise to life on Earth. ![]() Past research had revealed a range of building blocks of life in meteorites, such as the amino acids that make up proteins. ![]()
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