HESI A2 Biology Practice Test

Nucleotides in a DNA strand are connected by phosphodiester bonds. These specialized covalent bonds form between the phosphate group of one nucleotide and the hydroxyl group on the sugar of another nucleotide. This linkage creates a backbone for the DNA structure, consisting of alternating sugar and phosphate groups.

The phosphodiester bond is crucial for the integrity and stability of the DNA molecule, allowing it to maintain its structure during replication and protein synthesis. It is important to note that while hydrogen bonds are involved in holding the two strands of the DNA double helix together (between the nitrogenous bases), they do not connect the nucleotides of a single strand. Ionic and typical covalent bonds do not play a direct role in forming the primary structure of DNA in the same way that phosphodiester bonds do.