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transported out of the nucleus to get translated.

Genetic Code and Study of Mutations
Genetic Code

● Genetic code directs the sequence of amino acids during the synthesis
of proteins.

● George Gamow proposed that if 20 amino acids are to be coded by 4

bases, then the code should be made up of three nucleotides. 4​= 64
3​

(4​= 16), which is less than 20; so, the codon was proposed to be
2​
triplet.
● Har Gobind Khorana developed a chemical method to synthesise RNA

molecules with defined combination of bases.
● Nirenberg developed cell­free systems for protein synthesis, which

helped the code to be deciphered.
● The enzyme known as Severo Ochoa enzyme (polynucleotide
phosphorylase) helped to polymerise RNA with defined sequences in a

template independent manner.
● It finally gave rise to the checker­board for genetic code.