What is the function of the phosphate group in a DNA nucleotide?

The function of the phosphate group in a DNA nucleotide is to form the backbone of the DNA strand. In the structure of DNA, nucleotides are linked together through phosphodiester bonds, which connect the phosphate group of one nucleotide to the sugar of the next nucleotide. This linkage creates a strong, stable backbone that supports the overall structure of the DNA molecule.

The backbone is essential, as it provides structural integrity to the double helix and allows the nitrogenous bases to protrude from it. The bases, which contain the genetic information, pair with complementary bases on the opposite strand, while the phosphate-sugar backbone maintains the framework of the DNA helix.

While other options relate to the overall function of DNA, such as storing genetic information (which is indeed a primary role of DNA) and connecting with nitrogenous bases, these processes rely on the integrity of the phosphate-sugar backbone established by the phosphate groups. In the case of providing energy for DNA synthesis, it is the triphosphate version of nucleotides, like ATP, that supplies energy for the formation of new DNA strands during replication, not the phosphate group itself in the context of the nucleotide structure.