Use of radioactive thymidine to detect distribution of newly synthesized DNA in the chromosomes was performed on Vicia faba (faba beans) by Taylor and colleagues in 1958. The experiments proved that the DNA in chromosomes also replicate semiconservatively.
The chemical method developed by Har Gobind Khorana was instrumental in synthesizing RNA molecules with defined combinations of bases (homopolymers and copolymers). Marshall Nirenberg's cell-free system for protein synthesis finally helped the code to be deciphered. Severo Ochoa enzyme (polynucleotide phosphorylase) was also helpful in polymerizing RNA with defined sequences in a template independent manner (enzymatic synthesis of RNA).

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