Which type of bond joins the nitrogenous bases in a DNA molecule?

The type of bond that joins the nitrogenous bases in a DNA molecule is hydrogen bonds. In DNA, the nitrogenous bases—adenine, thymine, cytosine, and guanine—pair specifically (adenine pairs with thymine and cytosine pairs with guanine) through hydrogen bonds. These bonds are relatively weak compared to covalent bonds, allowing the DNA strands to separate easily during processes such as DNA replication and transcription.

The specificity and relative weakness of hydrogen bonds are crucial for the function of DNA, as they enable the double helix structure to remain stable while also allowing for necessary biological processes to occur. The formation of hydrogen bonds contributes to the complementary base pairing that ensures accurate genetic information is maintained and passed on. Thus, this characteristic is fundamental to the structure and function of DNA.