Question

what did chargaffs rule state about dna bases?
there are no pairs when talking about bases
for every purine there is an equal amount of pyrimidines
the bases will always occur in sets of three
the bases will always occur in different ratios

Explanation:

Chargaff's rule is a fundamental concept in molecular biology. It states that in DNA, the amount of purines (adenine and guanine) is equal to the amount of pyrimidines (thymine and cytosine). This is because adenine pairs with thymine and guanine pairs with cytosine. The first option is incorrect as there are base - pairing rules in DNA. The third option about bases occurring in sets of three is related to codons (in mRNA for protein synthesis) not Chargaff's rule. The fourth option is wrong because Chargaff's rule implies a specific ratio (purine = pyrimidine) not different ratios.

Answer:

for every purine there is an equal amount of pyrimidines