In DNA, the base pairing rules state that Adenine (A) pairs with Thymine (T), and Guanine (G) pairs with Cytosine (C). Therefore, the percentage of Guanine should be equal to the percentage of Cytosine.
If we denote the percentage of A as \( p(A) \), T as \( p(T) \), G as \( p(G) \), and C as \( p(C) \), we have the following relationships:
- \( p(A) + p(T) + p(G) + p(C) = 100% \)
- \( p(A) = p(T) \)
- \( p(G) = p(C) \)
Given the percentages in the options:
- a) 17%
- b) 33%
- c) 50%
- d) 83%
We need to find a possible percentage of Guanine.
If we assume a base equal composition, with \( G \) and \( C \) comprising x% each, and A and T comprising y% each, we can set up the equations:
- Since \( p(A) = p(T) \) and \( p(G) = p(C) \), let \( p(A) = p(T) = y \) and \( p(G) = p(C) = x \).
- Then \( 2y + 2x = 100% \) simplifies to \( y + x = 50% \).
From this, since Guanine should equal Cytosine, if Guanine percentage is x%, we can check against the provided options:
If we choose \( p(G) = p(C) = x = 33% \):
- \( y = 50% - x = 50% - 33% = 17% \).
This satisfies:
- \( p(A) = p(T) = 17% \)
- \( p(G) = p(C) = 33% \).
Thus, the expected percentage of Guanine (G) in the sample would be 33% (option b).
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