Final answer:
During DNA or RNA synthesis, a phosphodiester bond is formed between the 5'-phosphate group of one nucleotide and the 3'-hydroxyl group of the next nucleotide in an antiparallel direction.
Step-by-step explanation:
During DNA or RNA synthesis, the 5'-phosphate of the nucleotide forms a phosphodiester bond with the hydroxyl (-OH) on the 3'-carbon of the polynucleotide chain. This process occurs in an antiparallel direction, where the 5' end of one nucleotide is bonded to the 3' end of the next nucleotide.