What type of bond holds the strands of DNA together?

The strands of DNA are held together primarily by hydrogen bonds, which form between complementary nitrogenous bases on opposite strands. Each base pairs specifically: adenine pairs with thymine through two hydrogen bonds, and guanine pairs with cytosine through three hydrogen bonds. This complementarity and the relative weakness of hydrogen bonds compared to other types of bonds allow DNA strands to separate and rejoin during processes such as DNA replication and transcription, making them essential for the functions of genetic material.

In contrast, covalent bonds are responsible for the strong links between the sugar and phosphate groups within the DNA backbone, providing structural integrity to each individual strand. Ionic bonds do not play a significant role in holding DNA strands together; rather, they are usually involved in attracting various ions and stabilizing protein structures. Peptide bonds, on the other hand, are specific to proteins, linking amino acids together, and are not relevant to the structure of DNA. Thus, the nature of hydrogen bonds is key to understanding how the DNA double helix maintains its stability while also allowing for replication and genetic expression.