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?

155. 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?

1. Heterochromatin
2. Euchromatin
3. Both a) and b)
4. Neither heterochromatin nor euchromatin but only the nucleolus

 Answer: Euchromatin