题干

PI(碘化丙啶)具荧光,可与DNA及RNA结合,常用来显示细胞中DNA或RNA含量.为了解腺样囊性癌细胞的分裂周期与抑制药物作用时期,某研究所的实验过程如下:

取腺样囊性癌细胞平均分成两组,分别在普通培养基和含紫杉醇的培养基中培养24小时,各得细胞数16×103个、12×103个;然后用相关药品水解掉RNA,再将这些细胞置于PI溶剂中一段时间;最后通过检测仪测定这些细胞不同时期的DNA含量,结果如下图1、图2所示:

(1)除去RNA的酶是____ 酶.

(2)两图中A、C所表示的时期依次是____ .

A.G1期;M期 B.S期;M期    C.G1期;S期与M期     D.G1期;G2与M期

(3)显微观察腺样囊性癌细胞临时装片,不可能出现的分裂相是____ (多选)

(4)在普通培养基中,若一个腺样囊性癌细胞的细胞周期是20小时,则S期约为____ 小时.

(5)在紫衫醇培养基中培养,C期细胞量显著增加,则紫衫醇的作用可能有____ (多选).

A.抑制DNA复制   B.延长G1期    C.分解细胞核    D.影响微管蛋白合成   E.干扰G2期向M期进行.

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RNA水解,D,AC,5,DE

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    Yesterday the police were joined by more than 20 volunteers in the continuing search for the two missing teenagers, Vicky Gray and Tom Hunter, and their guide, Gavin Jones. The police said that they had disappeared during an adventure tour of Cape York Peninsula.

    This was the second day of the search and the police were now very worried about the safety of the three missing people.

    The police said that the search had covered a wide area, but the rain forest was thick and their work was made harder by the recent rain. Later on Chief Inspector (警官) Roger Fleet said, “The travellers had a radio with them. If they had been in trouble, they would have called us.”

    The three travellers left Cooktown very early on Saturday morning in a Toyota car. They took a small dirt road that runs down to the Daintree River, a dangerous river full of crocodiles (鳄鱼). Chief Inspector Roger Fleet said the tourists wouldn't have got into trouble if they had stayed on the main road.

    A photo of Vicky and Tom was found by a policeman under the “Be Careful about crocodiles” sign near the river. Why was the photo left behind? This is just one of the unanswered questions. Other questions are: Why was the photo left behind? Why was the Toyota parked and locked at the edge of the rain forest? The police said that the travellers had left a map of the area behind. Why? Why had someone drawn a cross on the point where the car is? Is this a sign? What does it mean? If anyone can give information or has seen these three young people, contact the local police in Cooktown.