Phosphate bonds connect to the 5'-hydroxyl group of one nucleotide to the 3'-hydroxyl group of the next nucleotide in a polynucleotide chain. Through these bonds, the nucleotides are linked together to form a backbone, which gives the nucleic acid its structural integrity and allows for the transmission of genetic information. The specific pattern and sequence of phosphate bonds are essential for the proper functioning of nucleic acids and play a crucial role in various cellular processes, including DNA replication, transcription, and protein synthesis.