Question
Biology Question on Molecular Basis of Inheritance
E. Coli about to replicate was placed in a medium containing radio active thymidine for five minutes. Then it was made to replicate in a normal medium. Which of the following observation shall be correct
A
Both the strands of DNA will be radio active
B
One strand radio active
C
Each strand half radio active
D
None is radio active
Answer
One strand radio active
Explanation
Solution
When E. coli is exposed to radioactive thymidine for a short period (5 minutes in this case), only one strand of the DNA will become radioactive. This is because DNA replication is a semi-conservative process. So, the correct observation is (B): One strand radioactive