Word: forme
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Dates: during 1970-1979
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Appearing before a Senate subcommittee on behalf of the Carter Administration, HEW Secretary Joseph Califano asked Congress to impose federal restrictions on recombinant DNA research, a new form of genetic inquiry involving E. coli. The urgency of Califano's request underlined the remarkable fact that a longtime dream of science, genetic engineering, is at hand -and, some fear, already out of hand. In laboratories across the nation, scientists are combining segments of E. coli's DNA with the DNA of plants, animals and other bacteria. By this process, they may well be creating forms of life different from...
...most of their genes), they possess much smaller closed loops of DNA, called plasmids-which consist of only a few genes. This extra bit of DNA-genetic small change, as it has been dubbed-serves a highly useful purpose. When two bacteria brush against each other, they sometimes form a connecting bridge. During such a "conjugation," a plasmid from one bacterium may be passed into the other...
Observing these bacterial tricks, molecular biologists began isolating various restriction enzymes. They had already discovered another type of bacterial enzyme, called a ligase (from the Latin word meaning to bind), which acted as a form of genetic glue that could reattach severed snatches of DNA. Using their new biochemical tools, the scientists embarked upon some remarkable experiments. As usual, they turned to their favorite guinea pig, a lab strain of E. coli, and soon they had learned to insert with exquisite precision new genetic material from other, widely differing organisms into the bacteria (see diagram...
...gibe seemed aimed particularly at another Stanford scientist, David Hogness, who was leading the way in a new form of genetic roulette, appropriately called "shotgun" experiments. Hogness was using enzymes to fragment the DNA of fruit flies and then was inserting the gene material piecemeal into bacteria. That way he could reproduce the inserted genes in vast quantities and discover their functions. The technique seems to be working. To date, he has managed to isolate and identify 36 of the thousands of the fruit fly's genes. But critics fear that because the nature of many of the genes...
...process, scientists place the bacterium in a test tube with a detergent-like liquid. This dissolves the microbe's outer membrane, causing its DNA strands to spill out in a disorderly tangle. Most of the DNA is included in the bacterium's chromosome, in the form of a long strand containing thousands of genes. The remainder is found in several tiny, closed loops called plasmids, which have only a few genes each and are the most popular vehicles for the recombinant technique...