问题 问答题

启动子的作用是什么原核生物启动子的结构特征是什么

答案

参考答案:启动子具有使得相应的聚合酶识别、结合及在合适的起始位点起始转录的作用,如果没有启动子的存在,聚合酶就无法正确地结合到合适的DNA序列上进行转录。原核生物启动子的结构特征:①大多数的原核生物启动子的-10左右的位置处(一般在-4~-13的范围之内)大多包含TATAAT序列或稍有不同的变化形式,可以用TATPuAT来表示,该序列称为Pribnow框,或-10序列。②大多数原核生物启动子在RNA聚合酶覆盖的部分还有一段共有序列,称为Sextama框,或-35序列,其共有序列为T82T84G78A65C54A45。③cAMP与其受体蛋白CAP的复合物的结合位点,称为CAP结合位点。该CAP结合位点包括两个部位,一个是在-70~-50的反向重复序列(位点Ⅰ),一个是在-50~-40(位点Ⅱ)。实验证实,该位点与CAP的复合物的结合促进了开放性启动子复合物的形成。

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Jerome Kern is often called the father of American musical theater. Kern is remembered for the hundreds of songs he wrote for musical plays and movies. Music historians say that Kern gave artistic importance to American popular music for the first time. And, they say, he led the development of the first truly American theater music.

Jerome Kern was born into a middle-class family in New York City in 1885. Jerome’s mother, Fanny, loved the piano. She began to teach Jerome how to play when he was very young.

Jerome was a quiet boy and not a top student. When he completed high school, his father said he would have to work in the family’s store. But he later came to believe that Jerome might do better in music than in business after all. So he let the boy go to Europe to study music, as almost all serious young musicians did at the time.

Jerome Kern began his career as a songwriter in theaters in London and New York City. Success came quickly. By the early nineteen twenties, Kern was a successful young composer for Broadway musical comedies. In one three-year period alone, he wrote music for nineteen shows.

Kern wanted to try something completely new. He thought a musical play should be a real work of art, not just a collection of songs and dances. Kern wanted to do a truly American musical, with real American characters and real situations.

In 1927, he found the story he wanted. It was the book “Show Boat” by American writer Edna Ferber. “Show Boat” takes place in the 1880 on a passenger steam boat that travels along the Mississippi River.

Kern died in 1945 at the age of sixty. But “Show Boat” has been performed thousands of times all over the world.

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