Word: helix
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Dates: during 1970-1970
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...will increasingly foul the already poisonous air. Partly because of the bad city air, architects design buildings with windows permanently closed. Thus massive air-conditioning systems must dangerously draw ever heavier loads of power-without, however, filtering out most of the pollutants. Unless the course along such a double helix of progressively contradictory demands is reversed, high-energy civilizations could find themselves literally in a dark...
...more than a decade, most scientists have accepted the "central dogma" of molecular biology without question. Stated simply, that dogma holds that the heredity information in living cells is always passed along in the same direction: from the "double helix" DNA molecule to the single-stranded messenger RNA molecule, which in turn directs the synthesis of protein-which is essential to all life. Since the end of May, however, investigators at three separate laboratories have stunned the scientific community by revealing that the central dogma is contradicted by the activities of cancer-producing viruses...
...task was formidable. Hidden in the chromosomes, genes are basically sections of an extremely complex molecule called deoxyribonucleic acid (DNA). Twisted together like a spiral staircase, or double helix, the twin strands of the DNA molecule are linked by "steps" composed of pairs of mutually attracting chemicals, or bases, called nucleotides. DNA contains only four different kinds of nucleotides, but they can be arranged in an endless variety of complex sequences. Each complete sequence-some including thousands of steps on the molecular staircase-is a single gene containing a coded message of heredity. With that message, the gene can order...