Word: cytoplasmic
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Dates: during 1960-1969
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Having ruled out both environmental and genetic influences, Williams can only suggest that there are "unknown factors" that affect heredity. Although the gene-bearing chromosomes duplicate themselves precisely in each new cell nucleus after the division of a fertilized egg cell, the little-understood structures and particles in the cytoplasm of the egg cell are not symmetrically arranged. During division, Williams suggests, one new cell may not receive the same quantity of the unknown factors as another, and the result is marked differences between the four armadillos-or between identical human twins-that eventually form from the same...
...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 her forever. Likewise...
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...
...CONTRAST, the highly-differentiated cells of more developed organisms are much more stable. Once a cell is programmed to fulfill a specific role, it will continue to do so. In this case continual messages to the cytoplasm are superfluous. Kafatos has been able to correlate stability and differentiation. He made this important discovery in a research project which began with an undergraduate, Julianne Reich '67, a former Bio 15 student now at the Medical School. The gland on the moth's face which produces large amounts of a single enzyme is an example of a highly differentiated organ. About...
After investigating the stability of RNA, Kafatos turned to possible mechanisms for transporting the RNA to the cytoplasm. Extending his Widener metaphor, he said the first possibility is similar to a Cliffie going into the stacks to obtain the book herself while the second is like her using the library's call system, having the book delivered up to the reading room. In the first possibility, the actual users of the genetic information, the ribosomes, or protein-synthesizing particles, may carry messenger RNA from the nucleus to the cytoplasm, the cite of protein synthesis. Second, there may exist a distinct...