Question

If a DNA sample consists of 42% guanine, what percentage of the other nitrogen bases does it contain?

Option 1: 28%
Option 2: 58%
Option 3: 14%
Option 4: 86%

Answer 1

If a DNA sample consists of 42% guanine, the percentage of the other nitrogen bases it contains is 14%.

Step-by-step explanation:

If a DNA sample consists of 42% guanine, we can use Chargaff's rules to determine the percentages of the other three nitrogen bases. According to Chargaff's rules, in DNA, the amount of guanine (G) is equal to the amount of cytosine (C), and the amount of adenine (A) is equal to the amount of thymine (T).

Since guanine (G) makes up 42% of the DNA sample, cytosine (C) would also make up 42%.

Therefore, the percentage of the other two nitrogen bases would be 100% - (42% + 42%) = 16%. So, the correct answer is Option 3: 14%.