Word: bacterias
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...summer of 1965, Schopf found fossilized remnants of bacteria in rock samples that Barghoorn had brought back from Africa. The fossil organisms -- from a Fig Tree formation in eastern Transvaal, South Africa -- were then the oldest form of life known...
...isolate the represser, Biophysicist Walter Gilbert and Biochemist Benno Muller-Hill decided to work with a species of simple bacteria called Escherichia coli, which have a healthy appetite for lactose, a sugar found in milk. The scientists knew that when lactose was available, the bacteria cells produced an enzyme that broke the sugar down into two simpler sugars that the cells could use. When only other nutrients were present, however, the amount of this enzyme was drastically reduced; a repressor apparently turned off the gene that controlled its production...
...premise that the lactose must have prevented the represser from turning off the appropriate gene -probably because it was attracted by the represser and combined with it chemically. With a sophisticated technique, they allowed radioactive lactose-like molecules that served as tracers to be attracted by a concentrate of bacteria cell material. Isolating and analyzing the substance that had combined with the tracer molecules, they discovered that it was a large protein molecule - their long-sought "lactose represser...
...Bursting Bacteria. In an equally complex experiment with the same type of bacteria cells, Harvard Molecular Biologist Mark Ptashne discovered a second represser - a smaller protein molecule that prevents the bacteria from bursting when they are attacked by viruses. Ptashne's experiment also indicated that the represser turned off the appropriate cell genes by binding itself tightly to them, somehow preventing the production of an enzyme in the process...
...count decreased, and so did the swelling of some of his organs. But his red-blood cells were being destroyed as an apparent side effect and treatment had to be stopped. The boy died of his leukemia. The problem of purification remains. Even the presumably safer material extracted from bacteria, in its currently purest form, causes allergic reactions in mice-as it did to some extent in the case of young Frank Hayes...