The pairing of the nitrogen bases in a DNA molecule is AT and CG. Let's say that the DNA strand has the sequence of ATCG. The complementary strand of that DNA strand will be TAGC. A and T & C and G must pair with each other. The replicated strand will be the same as the original strand because the complementary strand of the replicated strand will be ATCG, which is the same as the original strand.
