Correct Answer - A
The existence of triplet code was simply an assumption till 1961 , when Nirenberg and Matthaei proved its existence by experiments . They were able to synthesise artificial mRNA , which contained only one nitrogenous base , i.e. uracil.
This synthetic poly U sequence was then placed in a cell free system containing protein synthesising enzymes (extracted from bacterium E. coli) and 20 amnio acids together with necessary ATP . During the process , a small polypeptide molecule was produced , which was formed by the linking of phenylalanine.
This suggested that UUU is the code for phenyl alanine . Nirenberg got Nobel prize for his contributions.
