question_answer

E. coli about to replicate was placed in a medium containing radioactive thynidine for five minutes. Then it was made to replicate in a normal medium. Which of the following observation will be correct?

A) Both the strands of DNA will be radioactive

B) One strand radioactive

C) Each strand half radioactive

D) None is ladioactive

Correct Answer: B

Solution :

Since DNA replication is semiconservative, the newly synthesized strand of DNA would be normal while the strand obtained from parent molecule would be radioactive.