Question

a researcher analyzed several dna samples and measured the percentages of each base for each sample. the results are in the table:
percentages of bases in samples
sample a t g c
w 15 15 35 35
x 10 10 40 40
y 25 25 25 25
z 30 30 20 20
if the researcher had studied mrna instead, what percentage of uracil would be expected for sample x?
10%
15%
25%
40%

Explanation:

Step1: Recall base - pairing rules

In DNA, A pairs with T and G pairs with C. In mRNA, T is replaced by U, and A pairs with U.

Step2: Analyze sample X in DNA

In sample X of DNA, the percentage of adenine (A) is 15%.

Step3: Determine uracil percentage in mRNA

When DNA is transcribed to mRNA, the amount of A in DNA will be equal to the amount of U in mRNA. So if A in DNA of sample X is 15%, the percentage of uracil (U) in the corresponding mRNA will also be 15%.

Answer:

15%