Question

The table below shows the percentages of bases in a DNA sample. How much Adenine (A) should you expect to find in the sample?

Base
A
C
G
T
% of Total DNA

17

33

a
17%
b
33%
c
50%
d
72%

Answer 1

In DNA, the bases adenine (A) and thymine (T) pair together, as do cytosine (C) and guanine (G). According to Chargaff's rules, the percentage of adenine (A) should be equal to the percentage of thymine (T), and the percentage of cytosine (C) should equal the percentage of guanine (G).

From the table you provided, we have the following information:

- Percentage of A = 17%
- Percentage of C = 33%
- Percentage of G = a (which we need to determine)
- Percentage of T = 17%

Since A and T are equal, we can confirm:

- Percentage of T = 17%
- Percentage of G (c) must be equal to the percentage of C = 33%

To find the percentage of G, we already know it is 33%, hence:

- Percentage of G = 33%

This gives us a chance to check for the correctness of bases:

- A = 17%
- T = 17%
- C = 33%
- G = 33%

So the only base left to determine is T. Since A = T and C = G, the total percentage adds up to:

17% (A) + 17% (T) + 33% (C) + 33% (G) = 100%.

Thus, based on the provided data, the amount of adenine (A) in the sample is **17%**.