Word: celling
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Dates: during 1990-1999
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Consider for a moment a simple scientific fact: at the instant conception occurs, all that any microscope or documentary can show you is a single cell, dividing upon itself again and again, not taking recognizably human shape for many days. The reality of cellular infancy belies the genetic reality that exists fully at that same moment of conception. Painted to complex perfection on its landscape of DNA are the characteristics and flaws, talents and proclivities of an individual. These are facts that science has given us. This is a truth that the arbitrary nature of the Roe V. Wadetrimester system...
Scientists have long theorized that a cell's biological clock lies in its telomeres, little bits of DNA that coat the tips of the chromosomes and, much like the plastic cuffs on shoelaces, prevent the strands from unraveling. Every time a cell splits in two, the telomeres shorten, until finally, after about 40 to 90 divisions, they are reduced to stubs. Because any further divisions would fray the chromosomes, the cells settle into a twilight stage and eventually die. Only an enzyme called telomerase, first discovered in 1984, can repair the damaged telomeres. However, most human cells, with the exception...
Fast-forward to last summer, when three different groups of researchers cloned a gene that makes it possible to reactivate telomerase in human-tissue samples. The race was on to see who could make cells live longer than they normally do. Researchers from Geron and the University of Texas Southwestern Medical Center at Dallas infected normal cells with a virus that had been genetically engineered to switch telomerase on. In every case the cells' telomeres lengthened instead of shortening, while the cells stayed healthy and continued to divide. "When we submitted the paper, we were at 20 generations past...
There's quite a difference, however, between getting a few cells to live longer and increasing even a single human life-span. Doctors are already familiar with cells that live indefinitely: they're called cancer cells. Apparently one reason tumors expand aggressively is that their cells are full of telomerase. So, unless scientists carefully control cell division, activating human telomerase may not prolong life but just create cancers...
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