33P is a radioactive isotope of phosphorus. Can 33P be used to make a radioactive nucleotide?

• A. No, because radioactive isotopes cannot be incorporated into biological molecules.
• B. Yes, but only if the nucleotide contains sulfur.
• C. Yes, because phosphorus is a component of the phosphate group in nucleotides.
• D. No, because phosphorus is not found in nucleotides.

Answer: (C)

Verified step by step guidance

1. Recall the structure of nucleotides, which consist of three parts: a nitrogenous base, a sugar (ribose or deoxyribose), and one or more phosphate groups.
2. Understand that the phosphate group in nucleotides contains phosphorus atoms, which means phosphorus is an essential element in the backbone of nucleic acids like DNA and RNA.
3. Recognize that radioactive isotopes of elements naturally found in biological molecules can be incorporated into those molecules to trace or study them, as long as the isotope is chemically similar to the stable form.
4. Since 33P is a radioactive isotope of phosphorus, it can replace the stable phosphorus in the phosphate group without altering the chemical structure of the nucleotide.
5. Therefore, 33P can be used to make radioactive nucleotides because phosphorus is a component of the phosphate group in nucleotides.