Question

Radioactive thymidine when added to the medium
surrounding living mammalian cells gets incorporated
into the newly synthesized DNA. Which of the
following types of chromatin is expected to become
radioactive if cells are exposed radioactive thymidine
as soon as they enter the S-phase?
(A) Heterochromatin
(B) Euchromatin
(C) Both (A) and (B)
(D) Neither heterochromatin nor euchromatin but
only the nucleolus​

Answer 1

Answer:

Euchromatin is loosely packed DNA with higher gene concentration as compared to heterochromatin which is tightly packed and have less gene concentration, thus less DNA content. S phase includes replication of both euchromatin and heterochromatin DNA, the radioactive thymidine will be incorporated in both types of DNA. So, the correct answer is option C