Concept 22 DNA words are three letters long.
Marshall Nirenberg, Har Gobind Khorana, and Robert Holley shared the 1968 Nobel Prize for Physiology and Medicine. Nirenberg and Khorana cracked the genetic code. Holley sequenced and deduced the structure of the first tRNA molecule.
Har Gobind Khorana (1922-2011)
Har Khorana was born in Raipur, West Pakistan. His father was a clerk in the British Indian government. Although the family was not well-to-do, Khorana's father made sure that his children had an education.
Khorana went to Punjab University in Lahore and graduated with a Master of Science. In 1945, a fellowship from the government of India gave him the opportunity to study abroad. He went to the University of Liverpool where he obtained his doctorate.
Khorana spent the next few years doing post-doctorate work, first at the Eidgenössische Technische Hochschule in Zurich, then at Cambridge University with G. W. Kenner and Lord Alexander R. Todd. It was at Cambridge that Khorana developed an interest in proteins and nucleic acids.
In 1952, Khorana was offered a job at the University of British Columbia where he was able to work fairly independently on various research projects involving phosphate esters and nucleic acids. The work on the chemical synthesis of ribotrinucleotides for protein synthesis was initiated at this time.
In 1960, Khorana accepted a position in the Institute for Enzyme Research at the University of Wisconsin. He continued working on nucleotide synthesis and cracking the genetic code. For this work Khorana shared the 1968 Nobel Prize in Physiology or Medicine with Robert Holley and Marshall Nirenberg.
From 1970 until his retirement in 2007, Khorana was the Alfred P. Sloan Professor of Biology and Chemistry at the Massachusetts Institute of Technology. The Khorana Program was founded in his honor in 2007 by the University of Wisconsin-Madison, the Government of India, and the Indo-US Science and Technology Forum, with the mission to build a community of scientists, industrialists, and social entrepreneurs in the United States and India.
Nirenberg and Khorana did not know the sequence of their synthetic mRNAs. They deduced the sequence by varying the amounts of nucleotides added and calculating the probability of making specific codon sets.
Why is redundancy built into the genetic code? Why not just have the "extra" codons not code for anything at all?