At the end of the paper, the authors state that the Nitrogen of a DNA molecule is divided equally between two subunits and each daughter molecule receives one of these. a. Which component of a DNA nucleotide contains nitrogen? b. How could you label another part of the DNA and repeat these tests with another component?

Answer: the organic nitrogenous bases of the ''rung'' of DNA ladder (adenine, thymine, cytosine and guanine)

Assuming this is labeled with N-15. The labeled Nitrogen will appear in the nitrogenous bases of the DNA rungs. (A-T; C-G) If the labeled nucleotide undergoes one complete DNA replication then the two DNA bands produced will compose of one original parent DNA, and one new daughter DNA.

The parental DNA contains N-15, and therefore heavier than the lighter daughter DNA.

To label all the DNA so that the heavy strand is present in the new daughter DNA, both DNA is allowed to undergo one round of semi-conservative replication; the result will be; all the double DNA stands containing one strand of the heavier N-15 parental DNA, and one of the lighter parental DNA. This will be integrated into each fragments of nucleotide molecules. Therefore even if these DNA fragments are broken the integrated heavy and light strands will not be affected.

Nitrogenous bases, the phosphates on the side.

Explanation:

DNA is a chemical in the nucleus that carries genetic codes that will determine a trait.

It is composed of three parts, a four nitrogenous bases, a phosphate group and a deoxyribose sugar.

Together they form a structure that resembles a ladder.

The sides of the ladder are made up of sugar and phosphate backbone.

The rungs are made up of the nitrogenous bases.

Therefore, the nitrogenous base was the one containing the nitrogen.

Another part of the DNA that can be labelled is the Phosphate group found at the sides of the ladder.