The genetic material of yeasts, which are the simplest organisms to have DNA in organized chromosomes (and are used to make bread and beer), are the focus of still other labs. Some researchers look at the simple genomes of viruses, which are often considered to be in a biological netherworld since they can't live on their own, while others look at the slightly larger, circular genomes of bacteria. 106).Īnd, over the years, experimental approaches to the study of genetic material have been equally diverse. On another, such studies offer the opportunity to use new information about the structure and behavior of DNA for useful purposes: for example, improved understanding of DNA replication provides a means for controlling the unrestrained proliferation of DNA found in cancer cells (see Box beginning on p. On one level there is the sheer intellectual excitement of getting to know the ways of life on an intimate basis. Over the past 40 years, the incentives for pursuing such research have been many and diverse. Moreover, broad problems-such as the way DNA duplication fits into the total cell cycle, the ongoing process of cell growth and division-could be addressed (see Box beginning on p. Specific issues that were once beyond the scope of experiments-such as when does a cell know when to duplicate its genetic material and how does it do it?-could now be tackled. It triggered a desire to know more about the bricks, mortar, and embellishments that filled out the basic architecture of DNA described by Watson and Crick and the precise building mechanisms used to construct it. Yet it marked the beginning, not the end, of a new era of biological research. This discovery was the culmination of decades of work by scores of researchers. Indeed, in a classic example of British-and scientific-understatement, Watson and Crick wrote in their landmark Nature paper that, ''It has not escaped our notice that the specific pairings (of bases in DNA) we have postulated immediately suggests a possible copying mechanism for the genetic material." What happens is that the bases on each of the parent strands become paired with their complements on the newlyįormed daughter strands. And because this physical structure involved a template where information from one DNA strand could be carried to another, it also hinted at how information could be passed from one generation to another with great fidelity. Their description of DNA as a twisted, ladder-like structure with rungs of complementary pairs of simple chemical bases offered a basic architecture for the genetic code. Although it had been known for hundreds of years that plants and animals had some sort of genetic material that carried information from generation to generation, what it was and how it worked remained unknown until 1953, when the American James Watson and the Englishman Francis Crick made their announcement from Cambridge, England. This year marks the forty-first anniversary of one of the most important scientific discoveries ever made: the finding that the universal genetic material is made of deoxyribonucleic acid, commonly called DNA.
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