Question

the analysis of a dna molecule reveals that 30% of its nucleotides are adenine. what percentage of the same dna molecule would be expected to be guanine nucleotides?
20%
30%
60%
70%

Explanation:

Step1: Apply Chargaff's rule

In DNA, \(A = T\) and \(G = C\), and \(A+T + G + C=100\%\). Given \(A = 30\%\), then \(T = 30\%\).

Step2: Calculate \(G + C\)

\(G + C=100\%-(A + T)=100\% - 60\% = 40\%\).

Step3: Find \(G\)

Since \(G = C\), \(G=\frac{G + C}{2}=\frac{40\%}{2}=20\%\).

Answer:

20%