Did life really start out in an RNA world?
Article Abstract:
It has been speculated that the first molecule of life was RNA, ribonucleic acid. A type of RNA, known as ribozymes, contain the two components necessary for the continuation of life: genetic information to code for the production of molecules involved in the processes of life, and the ability to act as an enzyme, or catalysis, to initiate the necessary functions of these molecules. The question of where the RNA originally came from four billion years ago, however, remains unanswered. If life began with RNA, then RNA must have been formed by spontaneous chemical reactions between simpler molecules. Precursor molecules could be formed from gases that were present at the time when life is thought to begin, such as water vapor, carbon dioxide and nitrogen, when hit with high energy from lightning or ultraviolet radiation. However, it is not known why RNA would be formed rather than other related molecules. RNA consists of the sugar ribose and four different base molecules, which are linked by the chemical phosphate. The linkage is not simple and the molecule forms a twisted shape. It would be thought that many molecules which are composed of the same constituents and are closely related but not identical to RNA would also have been formed, but these molecules are not found in nature. Some scientists posit that the molecule glycerol, which is similar to the ribose sugar in RNA except for one missing carbon atom, may have been the first molecule. However, there is no laboratory evidence that glycerol forms more complex molecules like ribose. Others believe that amino acids, which are the building blocks of proteins, could be formed spontaneously and were the first molecule. Debate, therefore, persists regarding the original molecule. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1989
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Catalytic RNA wins chemistry Nobel
Article Abstract:
The 1989 Nobel Prize in Chemistry was awarded to Sidney Altman of Yale University and Thomas R. Cech of the University of Colorado, Boulder. Their research has shown that RNA, ribonucleic acid, can function as an enzyme, a molecule that acts as a catalyst to accelerate biochemical reactions. Prior to their findings, proteins translated from RNA were thought to be the only molecules that could function as enzymes. This finding has major implications on the origin of life. It is questioned which existed first, proteins that could catalyze chemical reactions necessary in the processes of life, or nucleic acids which contained the genetic information to code for the proteins. RNA is now thought to be the primordial molecule, in that it contains genetic information and can also catalyze reactions. Cech's work showed that RNA by itself can remove introns, RNA that does not code for any of the amino acids which are the building blocks of proteins, from the mature RNA which codes for amino acids. Altman's work revealed the existence of complex molecules known as ribozymes, consisting of both RNA and protein, and demonstrated that the RNA portion acted as the enzyme or catalyst. These molecules also remove noncoding RNA. This research furthers the understanding of how molecules are synthesized and involved in the processes of life.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1989
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Computing at the speed of light
Article Abstract:
Researchers Harry Jordan and Vincent Heuring have developed the first general-purpose optical computer. The machine uses light rather than electrons to process and store information, and it stores and manipulates its own instructions internally.
Publication Name: Science
Subject: Science and technology
ISSN: 0036-8075
Year: 1993
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