what occurs during elongation of transcription. RNA is synthesized from the template and RNA polymerase moves along the DNA, elongating the RNA transcript molecule; an enzyme forms the hydrogen bonds between the bases of the DNA strand and the complementary bases of the RNA molecule found in the nucleus.hat occurs during elongation of transcription. RNA is synthesized from the template and RNA polymerase moves along the DNA, elongating the RNA transcript molecule; an enzyme forms the hydrogen bonds between the bases of the DNA strand and the complementary bases of the RNA molecule found in the nucleus.