问题
问答题 简答题
质粒的生物学特性有哪些？
答案
参考答案：
（1）质粒的主要成分：除酵母杀伤质粒为RNA分子外，已知的所有质粒为环状超螺旋DNA分子。
（2）质粒可以转移。
（3）质粒的复制依赖于宿主细胞。
（4）质粒带有许多选择标记，如抗药性基因、营养缺陷型基因、抗重金属基因等。
（5）质粒具有不相容性。
搜题请搜索小程序“爱下问搜题”
质粒的生物学特性有哪些？
参考答案：
（1）质粒的主要成分：除酵母杀伤质粒为RNA分子外，已知的所有质粒为环状超螺旋DNA分子。
（2）质粒可以转移。
（3）质粒的复制依赖于宿主细胞。
（4）质粒带有许多选择标记，如抗药性基因、营养缺陷型基因、抗重金属基因等。
（5）质粒具有不相容性。
综合填空：阅读短文，从方框中选择适当的词并用其正确形式填空，使短文通顺意思完整 。每空限填一词，每词限用一次, 有两个词是多余的。共10分。
Tom lived away from town . One day he went into town to buy something in the shop . and after he bought小题1: ________ he wanted, he went into a restaurant and sat小题2:________ at the table. When he looked round, he saw some old people小题3:________ eyeglasses on before小题4:________ their books, so after lunch he went to a shop to buy 小题5:________, too. He walked along the road, and soon found a 小题6: ________. The man in the shop made him 小题7:________ on a lot of glasses, but each time Tom said, “ No, I can’t read with these. ” The man became 小题8:________ and more puzzled (困惑) . At last he said, “ Excuse me, but 小题9:________ you read at all?” “ No, I can’t! ” Tom said, “小题10:________ I can read, do you think I will come here to buy glasses? ” |