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同类题1

现有3只毛色性别不同的豚鼠(二倍体):乳白色(♀)、银色(♀)、白色(♂).乳白色、银色、白色分别由Di、Ds、Da基因控制,有关基因的遗传遵循孟德尔遗传定律,基因间具有相同的显性表现形式.研究者利用这3只豚鼠做了相关的遗传试验,结果如下表:

亲本

子一代

子二代

乳白色(♀)×白色(♂)

全为乳白色(♀、♂)

乳白色:白色=3:1

(♀、♂中比例相同)

银色(♀)×白色(♂)

全为银色

(♀、♂)

银色、白色=3:1

(♀、♂中比例相同)

请回答:

(1)研究发现乳白色、银色、白色基因均由黑色基因Db突变形成,体现了基因突变具有____特点.对Db、Ds、Da基因的mRNA进行研究,发现其末端序列存在差异(见下图所示,其中起始密码子位置相同,UAA、UAG与UGA为终止密码子).

银色、白色性状的产生的根本原因分别是由于基因内部的碱基对____,导致Ds、Da基因控制合成的蛋白质中氨基酸分别发生了____ 、____ 的变化.

(2)银色、白色豚鼠杂交后代全为银色,这种显性现象的表现形式为____ 显性.

(3)F2中出现白色豚鼠的原因是____ .

(4)亲代、子一代、子二代的乳白色豚鼠的基因型分别是:____ 

(5)为了进一步探究乳白色与银色的显性关系,可利用子一代乳白色与银色雌雄豚鼠进行单对杂交(多组),用遗传图解进行分析并完成以下结果预测.若杂交后代中的表现型及比例为____ ,银色为显性.

同类题2

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    Mother's Day is a time of commemoration (纪念) and celebration for Mom. It is a time of breakfast in bed, family gatherings, and crayons scribbling "I Love You".

The earliest Mother's Day celebrations can be dated  (1)   to the spring celebrations of ancient Greece in honor of Rhea, the Mother of the Gods. During   (2)   , England celebrated a day called "Mothering Sunday". "Mothering Sunday" honored the mothers of    (3)  . In the United States Mother's Day was first suggested in 1872by Julia Ward Howe. In 1907, Anna Jarvis, from Philadelphia, began a campaign (运动) to establish (建立) a    (4)   Mother's Day. Ms Jarvis persuaded (说服) her mother's church in Grafton. West Virginia to celebrate Mother's Day on the second anniversary (周年纪念日) of her mother's   55  , the 2nd Sunday of May. And the next year Mother’s Day   56   in Philadelphia. Ms Jarvis and her supporters began to    57   officials, businessmen, and politicians in their quest to establish a national Mother’s Day. It was successful.   58    1911 Mother's Day was celebrated in almost every   59   . President Woodrow Wilson, in 1914, announced Mother's Day as a national holiday that was to be held on the 2nd Sunday of May each year.

While many countries of the world celebrate their own Mother's Day at   60   throughout the year, there are some countries such as Denmark. Finland, Italy, Turkey, Australia, and Belgium which also celebrate Mother's Day on the second Sunday of May.