Can people change their skin color without suffering like pop king Michael Jackson? Perhaps yes. Scientists have found the gene that determines skin color.
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 color of a dark-striped zebrafish（斑马鱼） to uniform gold by inserting a version of the pigment (色素) gene into a young fish. As with humans, zebrafish skin color is determined by pigment cells, which contain melanin (黑色素). The number, size and darkness of melanin per pigment cell determine skin color.
It appears that, like the golden zebrafish, light-skinned Europeans also have a mutation (变异) in the gene for melanin 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 zebrafish genes.
Humans acquired dark skin in Africa about 1.5 million years ago to protect bodies from ultra-violet rays of the sun (太阳光紫外线), 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 color, said Cheng.
The new discovery could lead to medical treatments for skin cancer. It also could lead to research into ways to change skin color without damaging it like chemical treatment did on Michael Jackson.
【小题1】 The passage mainly tells us that .A．people can not change their skin color without any painB．the new discovery could lead to research into ways to change skin color safelyC．pop king Michael Jackson often changed his skin color as he likedD．scientists have found out that people’s skin color is determined by the gene【小题2】 It can be inferred from the passage that .A．nowadays people who want to change their skin color have to suffer a lot from the damage caused by the chemical treatmentB．Europeans and Africans have the same geneC．the new discovery could help to find medical treatments for skin cancerD．there are two kinds of genes【小题3】Scientists have done an experiment on a dark-striped zebrafish in order to .A．find the different genes of humans’B．prove the humans’ skin color is determined by the pigment geneC．find out the reason why the Africans’ skin color is darkD．find out the ways of changing people’s skin color【小题4】The reason why Europeans are light-skinned is probably that A．they are born light-skinned peopleB．light-skinned Europeans have mutation in the gene for melanin productionC．they have fewer activities outsideD．they pay much attention to protecting their skin【小题5】The writer’s attitude towards the discovery is .A．neutral（中立的）B．negativeC．positiveD．indifferent（冷漠）D
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(答案→)D
解析：本文主要讲述基因决定人的肤色。
1. D 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。
2. A 推理判断题 从文章最后一句话得知，人们改变肤色会象迈克尔·杰克逊那样受到化学药品对皮肤的伤害。
3. B 细节理解题 根据第三段得知，因为斑马鱼和人类一样肤色中含有黑色素，所以科学家们以此来证明之。
4 B 推理判断题 根据第四段得知，因为欧洲人体内黑色素的基因发生了变异，所以他们的皮肤为浅肤色。
5. C 推理判断题 根据作者对基因决定人的肤色的论述以及文章首尾段可知，作者对此的态度是肯定的。