Nucleotides are exclusively added to the 3' end of the developing strand when DNA is produced in the 5'-to-3' orientation. The 5'-phosphate group of the new nucleotide attaches to the 3'-OH group of the final nucleotide of the developing strand.
Two chromosomes that are similar but not identical are called homologous chromosomes. When the chromosomes are duplicated, two identical chromosomes are called sister chromatids.
