Explain how the sea urchin and salmon data demonstrate both of Chargaff’s rules.

Chargaff’s rule states that there is equality in the number of complementary bases. It implies that an equal quantity of bases adenine(A) and thymine(T) exists. Similarly, an equal quantity of bases guanine(G) and cytosine(C) exists.

As the quantity of purine is equal to pyrimidine, the stoichiometric ratio between them should be 1:1. It implies that A:T or G:C should be 1:1.

In sea urchin, the base percentage of adenine and thymine are given as 32.8 and 32.1, respectively. The base percentage of guanine and cytosine are given as 17.7 and 17.3, respectively. It shows that adenine and thymine amounts and guanine and cytosine amounts are close and almost equal.

The ratio of adenine and thymine, which is 32.8:32.1, is approximately 1:1. The ratio of guanine and cytosine, which is 17.7:17.3, is approximately 1:1.

In salmon, the base percentage of adenine and thymine are given as 29.7 and 29.1, respectively. The base percentage of guanine and cytosine are given as 20.8 and 20.4, respectively. It shows that adenine equals thymine amounts and guanine equals cytosine amounts.

The ratio of adenine and thymine, which is 29.7:29.1, is approximately 1:1. The ratio of guanine and cytosine, which is 20.8:20.4, is approximately 1:1.

Therefore, the base percentages in sea urchin and salmon satisfy Chargaff’s rules: the amount of purine and pyrimidine are equal, and the complementary bases have a 1:1 stoichiometric ratio.