In sea urchin DNA, which is double stranded, 17% of the bases were shown to be cytosine. The percentages of the other three bases expected to be present in the DNA are: (NEET 2015) a. G-17%, A-33%, T=33% b. G-8.5%, A-50%, T=24.5% c. G-34%, A-24.5%,T=24.5% d. G-17%, A-16.5%,T=32.5%
Correct option is A) According to Chargaff’s rule all cellular DNAs, regardless of the species, number of adenosine residues is equal to number of thymidine residues which means that A=T; and the number of guanosine residues is equal to the number of cytidine residues; G= C. In the given question, there is 17% cytosine which means guanine percentage is also 17%. Thus, percent of G and cytosine = 34; percent of A+T= 100-34= 66; Adenine percent= 66/2= 33; thymine percent= 33. Thus, the correct answer is A.
