英语听力英语高级听力材料The Ghost In Your Genes.docx

1、英语听力英语高级听力材料The Ghost In Your GenesWe are on the brink of uncovering a hidden world, a world that connects past and future generations in ways we never imagined possible.What this means is an environmental exposure that your grandmother had could cause a disease in you even though youve never been e

2、xposed to the toxin. And you are gonna pass it onto your great-grand kids.These extraordinary discoveries have the potential to affect every aspect of our lives.Its not just the genes, but also the environment in the early life of your ancestors. Its not so much youre what you eat as something you a

3、re what your mother ate, and maybe you are what your grandmother ate. And if you take our data, youre whats stress your grandmother or grandfather had.It would change the way we think about our relationship with every generation.(it) Makes me feel closer to my children. What I experienced, in terms

4、of environment will have some type of legacy in my children and my grandchildren.The science of inheritance is being turned on its head.Were changing the view of what inheritance is.This small Swedish town may hold the evidence to launch a medical revolution. verkalix lies huddled on the edge of the

5、 Arctic Circle. Inaccessible and remote, it was cut off from the rest of the world for most of its history. Marcus Pembrey has traveled here to meet his colleague, Olov Bygren. They believe that the story lying buried in these graveyards may hold the proof to their radical ideas.Here we have at leas

6、t 2 generations.In the same grave.In the same .This group of people could contribute to really a sea change in the way we think about inheritance.They have come to this churchyard to find grandmothers and granddaughters, grandfathers and grandsons, connecting people who lived almost a hundred years

7、apart in entirely new ways, uncovering links that confound scientific thinking.Up to now, inheritance is just the genes, the DNA sequence. I suspect that were gonna be able to demonstrate that the inheritance is more than that.This is a grandson, as it were, in our study.It is the culmination of mor

8、e than twenty years work and for the first time, Pembrey is confronting the magnitude of their discovery.It really has come alive for me, coming here more than I had expected. Its really quite so, Im, sure about it, wonderful.Marcus Pembrey is one of a select band of scientists, a band of scientists

9、 who are daring to challenge an orthodoxy. They believe the lives of our parents, grandparents, and even our great grandparents can directly affect our well-being, despite never experiencing any of these things ourselves. To many, these ideas are regarded as scientific heresy.You can not predict whe

10、re important discoveries will be. The only thing that you can do is to follow your instinct.Conventional biology has always believed that our genetic inheritance is set in stone at the moment of our conception. At that instant, we each receive a set of chromosomes from both our mother and father. Wi

11、thin these chromosomes are the genes, strips of coded DNA, the basic unit of inheritance. After conception, it was assumed that our genes are locked away inside every cell of the body, protected and untouched by the way you live. So what you do in your life may affect you, but your genes remain unta

12、inted, unchanged for future generations. In classic genetics, your parents and grandparents simply pass on their genes. The experiences they accumulate in a lifetime are never inherited, lost forever as the genes pass untouched through generation after generation.The biology of inheritance was a rea

13、ssuringly pure process, or so it seemed. In the early 80s, Marcus Pembrey headed the clinical genetics department at Great Ormond Street Hospital for Children. He was frequently treating families with unusual genetic conditions.We were constantly coming across families which didnt fit the rules, did

14、nt fit any of the patterns that genetics were supposed to fit. So you think of chromosome abnormalities and you check the chromosomes and they are normal, so you then have to start imagining, as it were, you know, what might be underlying this and you were really driven to try and work it out becaus

15、e the families needed some help.The more families he saw, the more the rules of inheritance appeared to break down-diseases and conditions that simply didnt fit with the textbook conventions. One condition in particular caught his eye, Angelman syndrome.Named after Henry Angelman, the pediatrician w

16、ho first described Angelman syndrome. He referred to them as happy puppet children because it described, to some extent, the features. They have a rather jerky sort of movement when they are walking. These children have no speech. They are severely incapacitated in terms of learning, but are unchara

17、cteristically happy as they are smiling all the time.The condition was caused by a genetic fault: a key sequence of DNA was missing, deleted from Chromosome 15.Then we came across a paradox: at the same time, er, the same change, the same little deletion of Chromosome 15 had been clearly associated

18、with a quite different syndrome, much milder in terms of, er, of intellectual impairment, the Prader-Willi syndrome. These children are characterized by being very floppy at birth, but once they started eating properly and so on, they then had an insatiable appetite and would get very, very large.Wh

19、at Pembrey saw simply made no sense. Here were two completely different diseases, Angelman syndrome and Prader-Willi syndrome being caused by exactly the same genetic fault.So here were in a bizarre situation really, how could we have proposed that the same deletion could cause a, a different syndro

20、me?It appeared to Pembrey as if the simple view of inheritance was beginning to unravel, but his doubts were contrary to the tide of optimism sweeping the scientific community. In the early 1990s, the biggest project ever undertaken in biology was captivating the world.The Human Genome Project will

21、be seen as the outstanding achievement in the history of mankind.The Human Genome Project was to be the pinnacle of a century of work on genes and genetics. It seemed as if the secrets of life were at our fingertips.The genetic blueprint of mankind.Nothing else, merely the whole human genetic code i

22、s a set of instructions to make a human being.Human genome is like a Bible where everything was written down. The hope and the expectation was that once we had that book in front of us, and all the letters we could just read down the pages, and we would understand how the body was put together.It wo

23、uld offer a complete understanding of human biology at a molecular level. The hope was that once the code was written down, scientists could find the genetic cause and cure for every disease.The list is endless.We were thinking of genes in a very mechanical way. We were thinking of them just in term

24、s of the sequence of the letters when we were working out how we could work out what all the letters were in the book.Scientists estimated that the human genome, the book of life, would contain around 100,000 genes.And then when they started sequencing they, they realized there may be 100,000 genes,

25、 and it popped down to 60, and then it popped down to 50, I mean, and slowly went down to a much smaller number. In fact we found out that the human genome is probably not as complex and doesnt have as many genes as, as plants do. So that they made us really question it all. If the genome has less g

26、enes in this species versus this species, and we are more complex potentially, whats going on here?Now, scientists estimate there are probably less than 30,000 genes.We believed, I believed naively that we would be able to find the genetic components of common diseases. Thats proven to be very diffi

27、cult. The idea of one-gene-one-disease does not explain it all.30,000 genes didnt appear enough to explain human complexity. There had to be something theyd missed. The first hints of what was missing lay in the curious paradox of the Prader-Willi and Angelman syndromes, two quite different diseases

28、 caused by exactly the same genetic fault. When Pembrey looked at the inheritance pattern for their conditions he noticed something even stranger.What really mattered was the origin of the Chromosome 15 that had the deletion. If the deletion was on the Chromosome 15 that the child had inherited from

29、 father then you had Prader-Willi syndrome. Whereas, if the, er, deletion, er, was inherited from the mother, er, you had the Angelman syndrome.It was a complete surprise that the same missing strip of DNA could cause one disease when it came from the mother and a completely different disease when i

30、t came from the father. It was as if the genes knew where they came from.Youve got a developing fetus manifesting this condition. How does the Chromosome 15 know where it came from? It, there must have been a tag or an imprint placed on that chromosome during either egg or sperm formation in the pre

31、vious generation to, to say Hi, I came from mother, I came from father and we are functioning differently. So thats the key thing that although the DNA sequence is the same the different sets of genes were being silenced depending on whether it came from the mother or from the father.It showed that

32、there was clearly more to inheritance than simply the coded sequence of DNA.We then realized that we were dealing with what is now known as genomic imprinting. What genomic imprinting means is, in a nutshell, that genes have a memory of where they came from.Something other than just the DNA was capable of moving between generations. It was a tantalizing glimpse into this unknown and unexpected world. A hidden layer acting on and able to directly control how our genes function. It meant that inheritance was not simply about which genes you inherited, but whether thos