Word: rna
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...cells apparently have the same genetic information. That is, red blood cells, which produce hemoglobin, have the same information as muscle cells, although obviously have widely different functions. Cell specialization thus may depend on the process by which the cell chooses which genetic information to copy into RNA and, perhaps more importantly, to transport and use in the cytoplasm...
...selects which information to copy. Next, the Cliffie has to decide whether or not the book is worth reading after all. She may carry it with her to the reading room or she may immediately discard it in the stacks. Similarly, not all the information which is copied into RNA is transported to the cytoplasm. Finally, as the girl may postpone reading the tome once in the reading room, so sometimes the RNA message is not immediately utilized in the cytoplasm. On the other hand, the girl may fall in love with the book and decide to carry it with...
Kafatos points out that even if the nucleus of a fertilized egg is removed, the egg can still give rise to a very young embyro. This demonstrates that stable messenger RNA for making an embryo had been stored in the egg's cytoplasm. Storage may well be the level where the critical choice might reside in the cells of higher organisms. This is not the case for very simple cells like bacteria, where the genetic information is transcribed into RNA and immediately translated into protein. Kafatos explained that, due to the great instability of the bacterial world, bacteria...
...example of a highly differentiated organ. About 70 per cent of the protein made by this gland is one enzyme, "cocoonaise." The rest is proteins needed for cell maintenance and growth. The message for making the differentiation - specific protein is extra stable. That is, each molecule of cocoonaise - messenger RNA remains active in the cytoplasm for at least two days. By contrast, the rest of the cell's messengers only survive for a few hours. Presumably, their decay introduces flexibility in the non-specialized functions of the cell...
...stopped the synthesis of all RNA by treating the cells with the specific antibiotic Actinomycin D, which is, incidentally, used to stop the growth of cancer cells. From then on, all protein synthesis depended on pre-existing messengers. He detected new protein molecules by exposing the cells to radioactive amino acids, which are incorporated into any protein the cell synthesizes. Kafatos has made thin sections of the cell and covered them with a thin photographic film. The radioactivity behaves like light and activated the film. His process is called autoradiography. He could then develop the film, count the activated silver...