Question

Why do nucleotides only pair with certain other nucleotides?

Answer 1

Molecular structure. It is like liquids, and they only mix if the have the same things but nucleotides do the same thing.

Answer 2

Answer: Molecular structures

Explanation:

In DNA ladders, each rung is actually two bases, but each pair is paired with only one other base because of their molecular structure.

Hope this helps you.