DNA, the Keeper of Life's Secrets, Starts to Talk

1. Chapter 4 DNA, the Keeper of Life's Secrets, Starts to Talk By Nicholas Wade

2. More than fifty years ago, on Saturday, Feb. 28, 1953, two young scientists walked into the Eagle, a dingy pub in Cambridge, England, and announced to the lunchtime crowd that they had discovered the secret of life. By divining the chemical structure of DNA, the archive of life, James D. Watson and Francis Crick had seen how the molecule could encode information in the copious quantities necessary to program a living cell. DNA, the Keeper of Life's Secrets, Starts to Talk

3. The Watson-Crick discovery showed that DNA records genetic information in the form of a four-letter alphabet. But obtaining the text of the message that evolution has taken some four billion years to compile was no easy task. It was another 20 years, in the mid-1970's, beforeone of their Cambridge colleagues, Dr. Fred Sanger, worked out an ingenious method for determining the order of the letters in a stretch of DNA. The genome era began on May 25, 1995, when Dr. J. Craig Venter announced that he had decoded the first genome of a single-celled organism, a bacterium known as Haemophilus influenzae. Since then about a hundred bacterial, plant and animal genomes have been decoded. DNA, the Keeper of Life's Secrets, Starts to Talk DNA段 1. It will be two years before we meet again. 我们要过两年才能见面。 2. It will be two weeks before everything returns to normal. 两周之后一切才能恢复正常。 3.It was another seven years before they got married. 他们又过了七年才结婚。

4. As each genome is deciphered, the tree of life comes into clearer focus. Even creatures as far apart as man and mouse have turned out to possess amazingly similar sets of genes, each with a similar sequence of DNA units. So far each genome has turned out to have some novel genes special to its own species, as well as a core set having to do with the basic cell operations, which seem very ancient and probably trace back close to the origin of life. The ability, gift of the genome sequence, to track thousands of genes at the same time puts biologists in the position of being able to analyze the living cell in action as it does its housekeeping or responds to the ceaseless chatter of signals from its neighbors. DNA, the Keeper of Life's Secrets, Starts to Talk

5. The genomic era is bringing about a quantum leap in biologists' capabilities, drawing almost within contemplation one of biology's ultimate goals, that of understanding a whole organism in terms of its DNA. DNA is an unrivaled genealogical archive. By examining the DNA of the living, biologists can reach back and resolve many otherwise inaccessible questions. DNA evidence recently corroborated the folk legend, dismissed by almost all historians, that Thomas Jefferson quite likely had a second, unacknowledged family with his slave Sally Hemings. From the DNA of people living today, geneticists are drawing inferences about the size of the ancestral human population and tracking its movements across the globe as the first modern humans dispersed from Africa to remote corners of the globe. DNA, the Keeper of Life's Secrets, Starts to Talk

6. DNA has already been used to modify crops, building bacterial genes for countering insects into corn and cotton, and adding genes from daffodils and bacteria to help rice complete the biochemical pathway to make vitamin A. Implicit in the understanding of DNA is the possibility of changing it, a prerogative until now reserved for evolution. Gene therapy, the idea of patching up tissues by delivering the corrective form of an errant gene, has so far been a failure. Even when it works, its changes will not outlast the patient. DNA, the Keeper of Life's Secrets, Starts to Talk

7. But another approach, not yet technically possible or acceptable, is to change the human genome in a heritable way. Instead of devising costly drugs or therapies to treat the same diseases in each generation, why not go straight to the source and fix all known errant genes in the egg or sperm? Germ line genetic engineering, as it is called, would make permanent fixes to be passed from one generation to another. Advocates argue that however expensive it might be to produce each perfect baby, the cost would be a fraction of the lifetime health care otherwise needed. The DNA revolution is likely to provide the means to repair and improve the machinery of life. But human ideas for redesign, which might include items like perfect health and greater longevity, have little in common with evolution's procedure of natural selection, which thrives on mutation and mortality. DNA, the Keeper of Life's Secrets, Starts to Talk 种系基因治疗的立法原则分析 摘　　要: 自1990年世界首例基因治疗在美国成功以来，基因治疗作为一种全新的治疗方式开始受到人们的广泛关注。但是，尽管体细胞基因治疗已被大多数国家接受，种系基因治疗却依然受到排斥。这其中除了人们对目前尚无法评估的技术风险让人不能接受外，主要是伦理风险限制了人们的思维。然而，种系基因治疗虽然对伦理形成了一定的冲击，但它所具有的优点仍让广大不治之症患者看到了曙光。因此，通过法律规范来保证种系基因治疗科技的发展及维护伦理道德已成为各国立法的目标。 Children thriveon good food.  儿童靠良好食物而发育健壮。 Challenge is something we Americans thriveon.  挑战是我们美国人之所以兴旺的奥妙。 Some species of bateria thriveon simple compounds such as achohol.  有些种类的细菌在简单化合物上生长，如酒精。

8. Biologists recognize the depth of public concerns about genetic engineering. Yet most hope that the public can be educated to make what they regard as the right choices. Dr. Watson was among the group of scientists who warned in 1974 of the possible dangers of recombinant DNA, the technique that first allowed genes to be moved from one species to another. Though Dr. Watson soon decided those dangers were overblown, he still believes that scientists should talk frankly about the possibilities, good and bad, of their work. "It is far better to tell it as it is and take the risk," he said. "We should expect a constant concern from society as to where our knowledge is leading and whether to deploy it. That certainly existed in the past, for instance in the opposition to automobiles. But once you put someone in an auto you won't get them on a horse." DNA, the Keeper of Life's Secrets, Starts to Talk

9. Dr. Watson has recently become an advocate for being open to the idea of germ line genetic engineering. "Some think there is something wrong about enhancing people," he said. Dr. Crick, who has worked for the last 25 years on the problem of consciousness, says he does not expect it will yield to any sudden breakthrough. "At the origin of life things had to be simple," he said. "But when you come to consciousness it's probably a very late development in evolution." Both at the beginning of life and at its culmination, DNA has more to tell. DNA, the Keeper of Life's Secrets, Starts to Talk