Marshall Nirenberg (second left) explaining the genetic code to President Lyndon Johnson (second right)
Marshall Nirenberg at the NIH, 1999. He is holding one of the original charts with 'code-cracking' data.
Working out the base compositions for the codons in the genetic code.
Using charged tRNAs to prove triplet nature of the genetic code, and to determine the base sequences of codons
Doing the experiments to determine whether the genetic code is universal, and their subsequent philosophical impact.
Marshall Nirenberg talks about Cracking the code in the 1960s.
After the easy codons, exact triplets had to be made in order to finish deciphering the rest. Marshall Nirenberg and a group of scientists including Maxine Singer, Marianne Grunberg-Manago, Phil Leder were involved in this process. Har Gobind Khorana al
Marshall Nirenberg in his office at the NIH, 1960.
Paul Zamecnik first developed the cell-free extract system, which Marshall Nirenberg adapted to decipher the genetic code. Paul Zamecnik and Mahlon Hoagland also isolated activated tRNA, the "adaptor" that shuttled amino acids to ribsomes for incorporati
Marshall Nirenberg and Heinrich Matthaei used poly-U mRNA in a cell-free system to make a polyphenylalanine protein chain. This showed that UUU must be the code that specifies the amino acid phenylalanine.