# DNA was Extracted from a Bacterial Species. The Proportion of Cytosine was Found to be 30%, Then Calculate the Proportion of Purine.

According to Chargaff’s rule,

A+G = T+C

I.e., The amount of guanine is equal to cytosine, and the amount of adenine is equal to thymine.

C = 30%

Therefore, G = 30%

Out of 100% of bases, C and G make up the 60%.

Since A = T

A = T = 20%

Therefore, purines, adenine and guanine make up the 50% of the bases.

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