Question

A scientist is extracting the DNA of a multicellular organism. He finds that 20% of the strands bases are Thymine. Based on Chargaff's rule, what percentage of the
strands bases would be Adenine?

A. 20%
B. 70%
C. 40%
D. 60%

Answer 1

Answer:

A. 20%

Explanation:

A DNA molecule consists of four nucleotides viz: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). According to Chargaff in his complementary base pairing rule, these nucleotides pair with one another in such a way that A bonds to T, while G bonds to C.

Based on Chargaff's rule, the amount of Adenine in the DNA is equal to the amount of Thymine while the amount of Guanine is equal to that of Cytosine i.e. A=T, G=C.

A + T + G + C = 100%

Hence, in this question, a scientist finds that 20% of the strands bases are Thymine. This means that the amount of Thymine in that DNA will also be 20%. S

Since A=T = 20% in accordance to Chargaff rule.