E.coli cells having DNA radio labelled with 15N were placed in culture medium containing non radioactive N14 isotope for three generations. What will be the percentage of ratioactivity in DNA of the progeny?

Question

E.coli cells having DNA radio labelled with 15N were placed in culture medium containing non radioactive N14 isotope for three generations. What will be the percentage of ratioactivity in DNA of the progeny? (A) 50 % (B) 12.50 % (C) 25 % (D) 75 %

Tardigrade Admin · Accepted Answer

At start, both the strands of DNA will have radioactive isotope and thus radioactivity is 100 %. In next generation, after semi-conservative replication of DNA, 50 % radioactivity is found which is halved with each subsequent replication. Thus, after three generations, 12.5 % radioactivity will be found in bacterial culture.

Q. E.coli cells having DNA radio labelled with $^{15} N$ were placed in culture medium containing non radioactive $N^{14}$ isotope for three generations. What will be the percentage of ratioactivity in DNA of the progeny?

$50%$

$12.50%$

$25%$

$75%$

Q. E.coli cells having DNA radio labelled with 15N were placed in culture medium containing non radioactive N14 isotope for three generations. What will be the percentage of ratioactivity in DNA of the progeny?

50%

12.50%

25%

75%

Q. E.coli cells having DNA radio labelled with $^{15} N$ were placed in culture medium containing non radioactive $N^{14}$ isotope for three generations. What will be the percentage of ratioactivity in DNA of the progeny?

$50%$

$12.50%$

$25%$

$75%$