万物简史 第590期:生命的物质(16)
Still facing the possibility of being trumped at any moment, Watson and Crick applied themselves feverishly to the problem. It was known that DNA had four chemical components called adenine, guanine, cytosine, and thiamine and that these paired up in
万物简史 第591期:生命的物质(17)
Rosalind Franklin did not share in the Nobel Prize. She died of ovarian cancer at the age of just thirty-seven in 1958, four years before the award was granted. Nobel Prizes are not awarded posthumously. The cancer almost certainly arose as a result
万物简史 第592期:生命的物质(18)
Ninety-seven percent of your DNA consists of nothing but long stretches of meaningless garble junk, or non-coding DNA, as biochemists prefer to put it. Only here and there along each strand do you find sections that control and organize vital functio
万物简史 第593期:生命的物质(19)
The shape of a DNA molecule, as everyone knows, is rather like a spiral staircase or twisted rope ladder: the famous double helix. The uprights of this structure are made of a type of sugar called deoxyribose, and the whole of the helix is a nucleic
万物简史 第594期:生命的物质(20)
Most of the time our DNA replicates with dutiful accuracy, but just occasionally about one time in a million a letter gets into the wrong place. This is known as a single nucleotide polymorphism, or SNP, familiarly known to biochemists as a Snip. Gen
万物简史 第595期:生命的物质(21)
By such means does Darwinian natural selection look after us. It also helps to explain why we are all so similar. Evolution simply won't let you become too different not without becoming a new species anyway. 达尔文的自然选择理论正是以这样
万物简史 第596期:生命的物质(22)
(Junk DNA does have a use. It is the portion employed in DNA fingerprinting. Its practicality for this purpose was discovered accidentally by Alec Jeffreys, a scientist at the University of Leicester in England. In 1986 Jeffreys was studying DNA sequ
万物简史 第597期:生命的物质(23)
Altogether, almost half of human genes the largest proportion yet found in any organism don't do anything at all, as far as we can tell, except reproduce themselves. 据我们所知，总共有近一半的人类基因任何生物体内基因已知的最
万物简史 第598期:生命的物质(24)
The story was the same wherever researchers looked. They found that they could insert human DNA into certain cells of flies, and the flies would accept it as if it were their own. 同样的事情无处不在。研究人员将人类DNA植入果蝇某些
万物简史 第599期:生命的物质(25)
We have forty-six chromosomes, but some ferns have more than six hundred. The lungfish, one of the least evolved of all complex animals, has forty times as much DNA as we have. Even the common newt is more genetically splendorous than we are, by a fa
万物简史 第600期:生命的物质(26)
This is clearly a pity in one important sense, for if you had individual genes that determined height or propensity to diabetes or to baldness or any other distinguishing trait, then it would be easy comparatively easy anyway to isolate and tinker wi
万物简史 第601期:生命的物质(27)
In the early 1990s, scientists made an even more profound discovery when they found they could knock out supposedly vital genes from embryonic mice, and the mice were not only often born healthy, but sometimes were actually fitter than their brothers
万物简史 第602期:生命的物质(28)
Proteins, you will remember, are the workhorses of all living systems; as many as a hundred million of them may be busy in any cell at any moment. That's a lot of activity to try to figure out. 你可能记得，蛋白质是所有生命系统的役马：
万物简史 第603期:生命的物质(29)
It can all begin to seem impossibly complicated, and in some ways itis impossibly complicated. But there is an underlying simplicity in all this, too, owing to an equally elemental underlying unity in the way life works. All the tiny, deft chemical p
万物简史 第604期:冰河时代(1)
Part VI The Road To Us 第六部 通向我们的路 Descended from the apes! My dear, let us hope that it is not true, but if it is, let us pray that it will not become generally known. Remark attributed to the wife of the Bishop of Worcester after D
