Can people change their skin colour without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin colour. The gene es in two versions, one of which is found in 99 per cent of Europeans. The other is found in 93 to 100 per cent of Africans, researchers at Pennsylvania State University report in the latest issue of Science.
Scientists have changed the colour of a dark-striped zebra fish to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebra fish skin colour is determined by pigment cells, which contain melanosomes (黑色素体). The number, size and darkness of melanosomes per pigment cell determines skin colour.
It appears that, like the golden zebra fish, light-skinned Europeans also have a mutation (突变)in the gene for melanosome production. This results in less pigmented skin. However, Keith Cheng, leader of the research team, points out that the mutation is different in human and zebra fish genes.
Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun, which can cause skin cancer. But when modern humans leave Africa to live in northern latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng. Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colours, said Cheng.
The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin colour without damaging it like chemical treatment done on Michael Jackson.
【小题1】According to the passage, scientists have found .A．people living in northern latitudes need more sunlightB．the reason why people change their skin colourC．the reason why people get skin cancerD．the gene that determines skin colour【小题2】We can infer from the passage that .A．people like to change their skin colourB．a mutation in the gene for melanosome production is different in human and zebra fish geneC．people will be able to change their skin colour without chemical treatment in the futureD．skin cancer can be cured now【小题3】Which of the following is NOT mentioned according to the passage?A．The version of the pigment gene of Asians and that of Africans are the same.B．Scientists have succeeded in turning the colour of a dark-striped zebra fish into uniform gold.C．Dark skin can protect bodies from utral-violet rays of the sun.D．People like pop king Michael Jackson.【小题4】The passage is probably taken from .A．a novelB．a science reportC．a story bookD．a science fictionD
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(答案→)D
解析：文章大意：本文主要讲述基因决定人的肤色。但是科学家已经发现可以用化学药品改变肤色。
【小题1】主旨大意题：根据全文讲述的主要内容得知：科学家们发现人的肤色是由基因决定的。选D。
【小题2】推理判断题 从文章第二段的句子Scientists have changed the colour of a dark-striped zebra fish to uniform gold by inserting a version of the pigment (色素) gene into a young fish.：得知，人们可以用化学药品改变肤色。选C。
【小题3】细节理解题：从第四段的句子：Asians have the same version of the gene as Africans, so they probably acquired their light skin through the action of some other gene that affects skin colours, said Cheng. 可知A是对的，从第二段的句子：Scientists have changed the colour of a dark-striped zebra fish to uniform gold by inserting a version of the pigment (色素) gene into a young fish.可知B是对的，从第四段的句子：Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun, which can cause skin cancer.可知C是对的，但是文章没有提到人们喜欢杰克逊。选D。
【小题4】推理判断题，本文主要讲述基因决定人的肤色。但是科学家已经发现可以用化学药品改变肤色。所以是一篇科普文章，应该选自科学报告。选B。