Word: helixes
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...large molecules of deoxyribonucleic acid (DNA) in the chromosomes. Researchers had deduced that somehow DNA directs the cells to assemble amino acids into the proteins that form the basic structural material of all living beings and impart their characteristics. Then, in 1953, James Watson (author of The Double Helix] and Francis Crick put together more of the puzzle; they discovered that DNA consists of twin helices that are held together by regularly spaced links similar to the stairs of a spiral staircase...
Three-Letter Words. It was Watson and Crick who clarified the nature of the genetic code. They demonstrated that each stair of the double helix consists of a pair of chemical compounds called nucleotides. There are only four different kinds of nucleotides in DNA, but the order in which they appear along the length of the helix varies considerably, suggesting that they are arranged in a coded sequence. To be able to call up one of the 20 different amino acids using only four nucleotide "letters," scientists decided, each genetic code "word" has to be three letters long...
...Nirenberg, then an obscure young scientist at the National Institutes of Health, provided the biological Rosetta stone. After synthesizing a single helix with half-stairs that were the equivalent of only one of DNA's nucleotides-adenine (A)-he added it to a solution containing all 20 amino acids. Only one protein was produced in the solution. It consisted entirely of a chain of amino-acid molecules called phenylalanine. Thus, Nirenberg concluded, a three-letter code word made up of adenine nucleotides (AAA) was nature's instruction to the cell to use phenylalanine in building a protein...
...Double Helix, James Watson's personalized account of the discovery of the structure of DNA, the master molecule of life, had one important side effect. It shocked many scientists into the realization that they are public figures-and fair game for biographers, critics and even gossip columnists. Last week the point was driven home again by the publication of another gossipy book, Lawrence and Oppenheimer, in which Author Nuel Pharr Davis calls the roll of America's nuclear greats. He judges them not only as scientists, but also as human beings. Some do not fare too well...
...Double Helix, Watson...