Word: amino
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...life's great unexplained chemical quirks: the 20 amino acids found in all living things almost always have the same geometric configuration. The structure can best be demonstrated by crystallizing the amino acids and passing polarized light through them; the light waves are always rotated to the left. Yet after an organism dies, its amino acids undergo a radical change. The lefthanded molecules gradually become righthanded. Although it has long been known that the mirror-like reversal progresses steadily as time passes, a practical use for the phenomenon has now been suggested: it can be used as a geological...
Bada decided amino acids might help open those pages. Using standard lab equipment, he found that it was an easy matter to measure the ratio of left-handed to righthanded molecules in a common amino acid called isoleucine, and he was able to estimate the age of fossils from that ratio. What is more, his tests required only a tiny sampling of material and could be completed in a few hours. There is one serious hitch, he reports in Earth and Planetary Science Letters. Because the rate at which amino acids change their configuration varies significantly with heat, the temperature...
...frozen carbon dioxide, or dry ice) than anyone had supposed. Mariner has also discovered four craters that the U.S. Geological Survey's Harold Masursky and others believe are extinct volcanoes, one of them relatively young. Exobiologists are excited by the finding because they think that most of the amino-acid-building gases in the earth's primordial atmosphere were belched forth by volcanoes...
...presented evidence that seemed to rule out the possibility. Although amino acids can be assembled in two ways?one a mirror image of the other?most of those found in terrestrial life have a left-handed configuration; that is, polarized light waves passed through them are rotated slightly to the left. Yet, when Ponnamperuma tallied up the meteorite's amino acids, he found an almost equal distribution of left-and right-handed molecules. That, he felt, was a clear sign that they had come from space...
...molecules of gases recently detected in the far reaches of space - ammonia, methanol, formaldehyde and formic acid - in various combinations. Then, keeping the gases completely free of water, the scientists exposed them to ultraviolet radiation and found that they combined to produce small quantities of some of the amino acids essential to life. Says Wollin: "Perhaps liquid ammonia, with its physical and chemical properties so similar to water, could serve as a solvent medium for waterless life...