Word: mitochondria
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...began, senior Anne Zager's school day is still going strong. She has been on the move since a 4:45 a.m. cross-country practice. She only just got home from a 2 1/2-hour drama rehearsal at school. Now she's crouched over the kitchen table, learning about cell mitochondria for a fast-approaching test. "I don't think it's physically possible for me to go to bed before midnight," she says...
...They also thrive, multiply and compete within our minds. When we announce to the world a good idea, who knows what subconscious quasi-Darwinian selection has gone on behind the scenes inside our heads? Our minds are invaded by memes, as ancient bacteria invaded our ancestors' cells and became mitochondria. Cheshire Cat-like, memes merge into our minds, even become our minds...
...living creatures share a certain genetic heritage. But comparing a 378-unit sequence of DNA taken from mitochondria within a Neanderthal cell to modern DNA, Paabo's team found striking differences. Contemporary humans differ from one another by an average of eight variations in that sequence. The Neanderthal specimen differed in 27 places. By comparison, there are only 55 differences between modern humans and chimpanzees...
...caveat. Despite its chewy theme, Brainfood is in many respects user- hostile. The author is director of research at the National Institute for Medical Research in Paris; his chapters on nutritional basics bristle with such forbidding terms as neuropeptides, mitochondria and oligodendrocyte. Nonetheless, those who can surmount this barbed-wire fence of technical jargon may find other parts of Bourre's book no less pleasing than -- to cite one of his own examples -- an omelet with freshly picked Bordeaux cepe mushrooms...
Most of the DNA in human cells is in the cell nucleus, in the form of chromosomes. Since chromosomes come from both parents, this nuclear DNA is reshuffled with each generation, confusing the line of inheritance. But there is also DNA outside the nucleus, in mitochondria, substructures within each cell that are responsible for producing energy the cell needs. Since the sperm's mitochondria do not survive fertilization intact, mtDNA is inherited solely through the mother. The only way it can change over the generations is through mutation. And that mutation, evidence suggests, proceeds at a steady, known rate...