For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to radioactively label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Why won't this experiment work? a. Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long. b. There is no radioactive isotope of nitrogen. c. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. d. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

Question

Biology

Madeleine Conrad

23 February, 10:43

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to radioactively label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogen atoms. Thus, labeling the nitrogen atoms would provide a stronger signal than labeling the phosphates. Why won't this experiment work? a. Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long. b. There is no radioactive isotope of nitrogen. c. Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive. d. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

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Answers (1)

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Lorena Lin · Answer 1

The correct option is D. Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

Explanation:

Nitrogen is an active constituent of amino acids which make up proteins. Nitrogen is also an active constituent of the nitrogenous bases which make up an organism's DNA.

Phosphorus is actively present in the DNA but amino acids lack phosphorus.

Our body is actively made up of DNA and proteins. If the nitrogen was radioactively labelled, the experimental results would be wrong as proteins also have nitrogen in them.