1.Suppose radioactive thymine was added to an actively dividing culture of E. coli bacteria. What would happen if a cell replicated once in the presence of this radioactive base?
A. Only one daughter cell would have radioactive DNA
B. Neither of the two daughter cells would be radioactive
C. All four DNA bases would be radioactive
D. Radioactive thymine would pair with nonradioactive guanine
E. DNA in both daughter cells would be radioactive
译文
1.假设放射性胸腺嘧啶被添加到大肠杆菌的主动分裂培养物中。如果一个细胞在这种放射性碱的存在下复制一次,会发生什么?
A. 只有一个子细胞具有放射性DNA
B. 这两个子细胞都不会具有放射性
C. 所有四个DNA碱基都将具有放射性
D. 放射性胸腺嘧啶将与非放射性鸟嘌呤配对
E. 两个子细胞中的DNA都是放射性的
答案:E
2.If radioactive sulfur (35S) is used in the culture medium of bacteria that harbor bacteriophage viruses, it will later appear in:
A. Bacterial RNA
B. Bacterial cell wallsBacterial cell walls
C. Bacterial cell walls
D. Viral RNA
E. Viral coats
2.如果在含有噬菌体病毒的细菌培养基中使用放射性硫(35S),它将在以后出现在:
A. 细菌核糖核酸
B. 细菌细胞壁细菌细胞壁
C. 细菌细胞壁
D. 病毒核糖核酸
E. 病毒皮毛
答案:E