Question

Which of the following are not part of Chargaff's rules?

a. Moles purines= moles pyrimidines
b. Moles A = moles T
c. Moles G = moles C
d. The DNA double helix is anti-parallel
e. All of the above

Answer 1

The statement not part of Chargaff's rules is that the DNA double helix is anti-parallel. Chargaff's rules focus on the equality of base pairs A=T and G=C, whereas the anti-parallel nature of DNA strands is a structural feature, not one of the rules.

Step-by-step explanation:

Among the options provided, the statement that is not part of Chargaff's rules is that the DNA double helix is anti-parallel. Chargaff's rules specifically state that the amount of adenine (A) is equal to the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C), thus affirming a 1:1 ratio for these base pairs across different species. While the anti-parallel nature of the DNA strands is a critical aspect of DNA structure, it isn't one of Chargaff's rules themselves, which focus exclusively on the ratios of nitrogenous bases. Therefore, option d. The DNA double helix is anti-parallel, is the correct answer.