Question

There is always a 1 to 1 correspondence between the number guanines (G) and the number of cytosines (C) in a DNA molecule. The same is true of the relationship between adenine (A) and thymine (T). Of course Professor Floop knows this. He analyzed a strand of DNA and determined the amounts of C and G it contained. If the molecule was 22% G, what was the percentage of A, assuming that DNA only contains G, C, A, and T

Answer 1

the strand contains 28% of adenine.

Explanation:

We have only four components, and we only know one of them:

`\left[\begin{array}{cc}C&?\\G&22\%\\A&?\\T&?\end{array}\right]`

Cytosine has a relation 1 to 1 with G, therefore the strand must contain the same amount of C as it posses G:

`\left[\begin{array}{cc}C&22\%\\G&22\%\\A&?\\T&?\end{array}\right]`

Therefore:

`A + T = 100\% - (C+G)`

This is because the strain only contains those 4 components.

since A and T have also a 1 to 1 relation, we can state that A = T in quantity.

So:

`A + A = 100\% - (C+G)`

`2A = 100\% - (22\%+22\%)`

`A = (100\%-44\%)/(2)`

`A = 28\%`