Question

While analysing the DNA of an organism, a total number of 5386 nucleotides were found, out of which the proportion of different bases were adenine = 18 %, guanine = 32 %, cytosine = 32 % and thymine = 18 %. Considering the Chargaff’s rule, it can be concluded that

• A. it is a single-stranded DNA
• B. it is a double-stranded DNA
• C. no conclusion can be drawn
• D. adenine is not equal to guanine and cytosine is not equal to thymine so the question is incorrect

Answer 1

The correct option is B it is a double-stranded DNA

For double-stranded DNA molecules, A + G = T + C. The A-T base-pair has two hydrogen bonds and the G-C base-pair has three hydrogen bonds. As the percentage of A = T and G = C, it is a double-stranded DNA.