Question

Radioactive thymidine is fed to cells about to enter S-phase. It will make radioactive

• A. Euchromatin
• B. Heterochromatin
• C. Both A and B
• D. Neither euchromatin nor heterochromatin

Answer 1

Answer: (C)

Both A and B

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.