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Introduction:
Earth, as it was when nearly formed, seemed an unlikely place for life to begin. Volcanoes splattered red hot lava over the grey rocky crust and the sun’s searing UV light scorched the surface. Lightning split the cloudy sky, and the harsh chemicals of the early atmosphere, such as carbon monoxide, would have poisoned almost any organisms living today. But scientists speculate that energy from lightning sunlight and volcanic eruptions eventually linked some of the atoms in the atmosphere into simple organic molecules. And these molecules – which form the basic building blocks of the chemicals of life – then rained onto earth’s surface and into its warm and salty oceans. There, the molecules- called amino acids formed chains of proteins, which in turn linked up into the vital nucleic acids DNA and RNA.
Earth, as it was when nearly formed, seemed an unlikely place for life to begin. Volcanoes splattered red hot lava over the grey rocky crust and the sun’s searing UV light scorched the surface. Lightning split the cloudy sky, and the harsh chemicals of the early atmosphere, such as carbon monoxide, would have poisoned almost any organisms living today. But scientists speculate that energy from lightning sunlight and volcanic eruptions eventually linked some of the atoms in the atmosphere into simple organic molecules. And these molecules – which form the basic building blocks of the chemicals of life – then rained onto earth’s surface and into its warm and salty oceans. There, the molecules- called amino acids formed chains of proteins, which in turn linked up into the vital nucleic acids DNA and RNA.
The watery cradle of life:
When the originally rich rain hit earth, it ran over the surface rocks, collecting minerals on its way to the oceans. The seas were soon a nourishing soup, stirring together the chemical necessary for life. Amino acids linked up into long chains called proteins. Phosphates molecules, sugars, and organic bases combined to form nucleotides. And nucleotides in turn formed the nucleic acids DNA and RNA.
In modern cells, DNA holds on organism’s genetic information, RNA sends the information to the proteins, and the proteins start the chemical reaction necessary to carry out the instructions. Some scientists believe that RNA played a critical role in the origin of life, since it can can both hold genetic instructions, and like a protein, carry them out. In this scenario, DNA & protein would have evolved after RNA.
Chemicals of life in the laboratory:
In 1953 an American chemist named Stanely M. Miller attempted to recreate the conditions of the young planet in the laboratory. He filled a glass apparatus with a warm “ocean” and an “atmosphere” composed of methane, ammonia and hydrogen gases. He sent strong spark through the gases to imitate lightning. After only a day, Miller could detect amino acids in his miniature ocean. Later other experiment showed that these amino acids could even form microscopic hollow balls. These spheres – some of which look surprisingly like bacteria – grow by absorbing material from their surroundings. When they reach a certain size, buds develop, then split off. Such tiny protein spheres might have been the first ancestor of living cells.
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