Question

question 6 (1 point)
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if 19% of the nucleotides in a dna molecule contain adenine, what is the % of cytosine in the molecule?
62%
38%
19%
31%

Explanation:

Step1: Recall base - pairing rules

In DNA, \(A = T\) (adenine pairs with thymine) and \(C = G\) (cytosine pairs with guanine). Given \(A=19\%\), then \(T = 19\%\)

Step2: Calculate the sum of \(A + T\)

\(A+T=19\% + 19\%=38\%\)

Step3: Calculate the sum of \(C + G\)

Since \(A + T+C + G = 100\%\), then \(C + G=100\%-(A + T)=100\% - 38\% = 62\%\)

Step4: Calculate the percentage of \(C\)

Because \(C = G\), so \(C=\frac{C + G}{2}=\frac{62\%}{2}=31\%\)

Answer:

31%