According to Chargaff’s Rule, in any double-stranded DNA molecule, the amount of Adenine (A) is equal to the amount of Thymine (T), and the amount of Cytosine (C) is equal to the amount of Guanine (G). This means that A pairs with T and C pairs with G.
If 15% of the nucleotides are Adenine, then there must also be 15% Thymine, since they are in equal amounts. Together, these two nucleotides make up 30% of the total nucleotides.
This leaves 70% of the nucleotides to be divided equally between Cytosine (C) and Guanine (G). Therefore, the percentages of Guanine and Cytosine will each be half of the remaining 70%.
So,:
- 15% (A) + 15% (T) = 30%
- Remaining = 100% – 30% = 70%
- 70% divided by 2 = 35%
Thus, the percentage of Guanine (G) in this DNA strand is 35%.