A

　　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 comes in two versions, one of which is found in 99 per cent of Europeans.The other is found in 93 t0 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 deter-mined

　　by pigment cells，which contain melanin(黑色素).The number,

　　size and darkness of melanin perpigment 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 pigrnented skin.

　　However, Keith Cheng, leader of the research team, points out that the mutation is different in hu-man ancl zebrafish genes.

　　Humans acquired dark skin in Africa about l.5 million years ago to protect bodies from ultra - violetrays of the sun. which can cause skin cancer.

　　But when modem humans leave Africa to live in northem latitudes, they need more sunlight on their skin to produce vitamin D. So the related gene changes, according to Cheng.

【湖南省汝城二中2014届高考英语一轮复习阅读训练 (15)】相关文章：

★ 【三维设计】2017届高考英语（江苏专用）二轮复习高考单词5大记忆法课件：3.谐音记忆法

★ 【北京专用】2014届高考英语一轮复习方案课时作业：必修5 Unit 4 Making the news

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (4)

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (14)

★ 贵州省贵阳市2014高考英语（新人教版）一轮阅读训练（39）附答案

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (2)

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (17)

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (54)

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (97)

★ 湖南省长沙县实验中学2016届高三英语二轮复习书面表达复习重点话题指导专题19 文学艺术话题指导（教师版）