What do phosphodiester linkages connect in a DNA strand?

Phosphodiester linkages are crucial in forming the backbone of DNA and RNA strands. They specifically connect the 5' phosphate group of one nucleotide to the 3' hydroxyl (-OH) group of another nucleotide. This linkage creates a continuous sugar-phosphate backbone that is essential for the structural integrity of nucleic acids.

The nature of this bond allows for the directional flow of genetic information, as nucleic acid strands have a defined 5' to 3' directionality, which is fundamental during processes such as replication and transcription. The phosphate group serves as a bridge between the nucleotides, linking them together in a polynucleotide chain. This connectivity not only establishes the backbone but also plays a significant role in the stability and overall structure of the DNA double helix.

Other options do not accurately describe the function of phosphodiester linkages. For example, connecting two base pairs does not involve any covalent bonds, as base pairs are stabilized by hydrogen bonds instead. Linkages between 3' -OH groups do not contribute to the formation of the DNA strand's backbone. Additionally, a linkage from the 5' phosphate to the nitrogenous base does not occur; the base is attached to the sugar portion of