histone (组蛋白)
参考答案：
组蛋白是真核生物染色体的基本结构蛋白，是一类小分子碱性蛋白质，有五种类型：H1、H2A、H2B、H3、H4，它们富含带正电荷的碱性氨基酸，能够同DNA中带负电荷的磷酸基团相互作用。
组蛋白的基因非常保守。亲缘关系较远的种属中，四种组蛋白（H2A、H2A、H3、H4）氨基酸序列都非常相似，染色质中的组蛋白与DNA的含量之比为1：1。
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| Amy was a little girl. She lived near a fruit shop in the village. The shop was __1__ by Mr. Smith. One day Mr. Smith said to Amy, "Would you like to earn (赚) some money? " "Oh, yes," replied she, "for I want some new shoes, and dad has no __2__ to buy them with." "Well, Amy," said Mr. Smith, "there are some fine __3__ in Mr. Green's garden, and he said that anybody was welcome to them. I will __4__ you thirteen cents (美分) a kilogram for all you will pick for me." Amy was so __5__ that she decided to go to pick the grapes as soon as possible. She ran home to get a __6__ at once. Then she thought she would like to know how much money she would get __7__ she picked five kilograms. __8__ the help of her pencil, she found out that she would get sixty-five cents. "But supposing I should pick twelve kilograms," thought she, "__9__ should I earn then?" "Dear me," she said, after figuring (计算) a while, "I should earn one dollar and __10__ cents." Amy then found out what Mr. Smith would pay her for fifty, a hundred, and two hundred kilograms. It took __11__ some time to do this, and then it was so near lunch time that she had to __12__ at home until afternoon. As soon as lunch was __13__, she took her basket and __14__ to the garden. Some boys had been there before lunch, and all the fine grapes were picked. As she went home, she __15__ what her teacher had often told her — "Do your task at once; then think about it," for "one doer is worth a hundred dreamers." | ||||
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