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Multiple Choice
If a DNA double helix contains 28% thymine (T) nucleotides, what is the percentage of adenine (A) nucleotides?
A
28%
B
22%
C
72%
D
44%
Verified step by step guidance
1
Recall Chargaff's rules, which state that in a DNA double helix, the amount of adenine (A) equals the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C).
Given that thymine (T) makes up 28% of the nucleotides, use Chargaff's rule to determine that adenine (A) must also make up the same percentage, since A pairs with T.
Express this relationship mathematically as $\%A = \%T$.
Since the problem provides $\%T = 28\%$, substitute this value into the equation to find $\%A$.
Conclude that the percentage of adenine (A) nucleotides in the DNA double helix is equal to 28%.