The sides of the DNA ladder are primarily made up of two components: sugar molecules and phosphate groups.
More specifically, the DNA molecule is composed of a long chain of nucleotides, each of which consists of a sugar (deoxyribose), a phosphate group, and a nitrogenous base. The sugar and phosphate groups alternate along the backbone of the DNA, forming what’s often referred to as the ‘sides’ of the ladder. Each sugar molecule is connected to a phosphate group, creating a strong covalent bond that holds these components together.
The resulting structure resembles a twisted ladder, where the sugar-phosphate backbone forms the upright sides, and the nitrogenous bases (adenine, thymine, cytosine, and guanine) are paired in the middle like the rungs of the ladder. The specific pairing of the nitrogenous bases—adenine with thymine and cytosine with guanine—helps to maintain the overall structure and stability of the DNA molecule.