Elucidating the genetic code

The process of translation requires transfer RNAs specific for individual amino acids with the amino acids covalently attached to them, guanosine triphosphate as an energy source, and a number of translation factors.t RNAs have anticodons complementary to the codons in m RNA and can be "charged" covalently with amino acids at their 3' terminal CCA ends.The first elucidation of a codon was done by Marshall Nirenberg and Heinrich J.Matthaei in 1961 at the National Institutes of Health.

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The percentages of adenine and thymine in the molecule are always the same, as well as percentages of cytosine and guanine.

In order to determine the order of the sequence, trinucleotides were bound to ribosomes and radioactivaly labeled aminoacyl-t RNA was used to determine, which amino acid corresponded to the codon.

Nirenberg's group was able to determine the the sequences of 54 out of 64 codons.

Subsequent work by Har Gobind Khorana identified the rest of the code, and shortly thereafter Robert W.

Holley determined the structure transfer RNA, the adapter molecule that facilitates translation.