Question

the dna double helix can be compared to a twisted ladder. what makes up the rungs of the ladder? what makes up the sides of the ladder? what holds the structure together?

Explanation:

The rungs of the DNA double - helix (ladder) are made up of nitrogenous base pairs (adenine - thymine and guanine - cytosine). The sides of the ladder are composed of sugar - phosphate backbones. Hydrogen bonds between the base pairs hold the structure together.

Answer:

The rungs are made up of nitrogenous base pairs. The sides are made up of sugar - phosphate backbones. Hydrogen bonds hold the structure together.