题干

亨廷顿舞蹈症是一种遗传神经退化疾病,主要病因是患者第四号染色体上的Huntington基因(用字母H表示)发生变异,产生了变异的蛋白质,该蛋白质在细胞内逐渐聚集,形成大的分子团.一般患者在中年发病,逐渐丧失说话、行动、思考和吞咽的能力,病情大约会持续发展15年到20年,并最终导致患者死亡.在一次人口普查过程中,偶然发现一特殊罕见男患者,其病情延迟达30年以上.通过家谱发现,该男子的父亲患该病,母亲正常,但其外祖父和外祖母皆因患该病死亡.经基因检测,发现该男患者与其他患者相比,出现一个A基因.

(1)由该家族的情况判断,亨廷顿舞蹈症遗传方式为____

(2)出现A基因的根本原因是____ .从发病机理分析,A基因能够使病情延迟大30年以上,最可能的解释是____ 

(3)若已知A基因位于常染色体上且与H基因不在同一对染色体上.该男患者已经与一正常女性婚配,生一个正常男孩的几率是 ____  .若他们的第二个孩子已确诊患有亨廷顿舞蹈症,则该小孩出现病情延迟的几率是 ____  .

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答案(点此获取答案解析)

常染色体的显性遗传,基因突变,A基因通过控制相关酶的合成,分解变异蛋白,使病情延迟,,

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    More and more comment(评论) sections are being shut down online.

    Autumn Phillips had had enough. On August 19, the executive editor of the Quad-City Times in Iowa, and Illinois, US visited her website, qutimes. com, and saw a story about a man who had been shot to death. When she got to the readers' comments section at the end, she was shocked by what she saw. Below the story was a growing string of comments—a racist remark about democratic( 民主的) voters, a negative comment about police...So Phillips decided to do something she had been thinking about for a long time: she shut down the comment section.

    Phillips was not alone in making such a move. Last week, NPR announced it too was closing its online comments section. The decisions don't mean that the news outlets are no longer interested in what their audiences are thinking. Both stressed their eagerness to hear from readers and listeners on social networks. But both agreed that comments had deviated from their original intention. And so they had.

    In the early days of digital journalism, comments were seen as a key part of the new media, a wonderful opportunity for strengthening the dialogue between news producers and their audiences. It was a welcome change, given that for long many news organizations were far too separated from their readers. Much more back and forth conversation seemed like healthy and welcome evolutions. Sadly, that's not the way things turned out. Rather than a place for exchanging ideas, comments sections became the home of ugly name-calling, racism and anti-women language. Besides their poisonous quality, comments seem out of place today.

    “Since we made the announcement, I've received an outpouring of responses from our readers,”she says. “I've heard from parents whose children were hurt by our online comments. I've heard from people who said they wouldn't send in letters to the editor because they were attacked so fiercely by comments, and it wasn't worth it.”