A dish of animal cells was grown in the presence of radioactive phosphorous. The phosphorous largely ended up in nucleotides inside the actively growing animal cells. In which cellular structure or structures would you predict the majority of the radioactive phosphorous to accumulate?

• A. Rough endoplasmic reticulum
• B. The Golgi apparatus
• C. Rough endoplasmic reticulum and Golgi apparatus
• D. The Golgi apparatus and the nucleus
• E. The nucleus

Answer: (E)

Verified step by step guidance

1. Understand that phosphorous is a key component of nucleotides, which are the building blocks of nucleic acids like DNA and RNA.
2. Recognize that the nucleus is the cellular structure where DNA is housed and where RNA is synthesized, making it a primary site for nucleotide accumulation.
3. Consider the role of the rough endoplasmic reticulum and the Golgi apparatus, which are involved in protein synthesis and processing, not directly in nucleotide accumulation.
4. Acknowledge that the Golgi apparatus is primarily involved in modifying, sorting, and packaging proteins and lipids, not in nucleotide synthesis or storage.
5. Conclude that since nucleotides are primarily used in the synthesis of nucleic acids, the majority of radioactive phosphorous would accumulate in the nucleus, where these processes occur.