🇮🇳 Har Gobind
Khorana

His village had no school. His father, Ganpat Rai Khorana, was a government tax collector — the only literate man among the approximately one hundred families of Raipur, a small settlement in the Punjab of British India. He taught his children to read under a tree. Har Gobind Khorana was born into that village on January 9, 1922, the youngest of five children, in circumstances of absolute poverty. He received a scholarship to attend school in Multan, then another to study chemistry at Punjab University in Lahore. He graduated with distinction and obtained a government scholarship to pursue a PhD at the University of Liverpool. He completed it in 1948, the same year British India was partitioned and his birthplace became part of Pakistan. He had nowhere to return to. He became a citizen of the world — and one of its greatest biochemists.

After Liverpool, Khorana worked as a postdoctoral researcher in Zurich with Vladimir Prelog, a future Nobel laureate who recognized his exceptional talent and encouraged him to continue in organic chemistry. He then spent three years at Cambridge with Alexander Todd (another future Nobel laureate), where he became deeply interested in the chemistry of nucleotides — the molecular building blocks of DNA and RNA. These interests placed him at the precise frontier of the most important questions in biology in the early 1950s: the connection between the sequence of nucleotides in a gene and the sequence of amino acids in the protein it encodes. In 1952, Khorana moved to the University of British Columbia in Vancouver, where he built a research group and began the long experimental programme that would eventually answer those questions.

Following the discovery of DNA’s double helix by Watson and Crick in 1953, biologists knew that the sequence of nucleotide bases in DNA somehow encoded the instructions for building proteins. But the specific rules of this encoding — the genetic code — were unknown. The code had to specify which of the twenty amino acids each possible sequence of nucleotides called for. Since DNA has four bases (A, T, G, C) and proteins are built from twenty amino acids, the code must use triplets of bases — 64 possible combinations, more than enough for 20 amino acids. By 1961, Marshall Nirenberg and his colleague Heinrich Matthaei had identified the first codon. Khorana, working at the University of Wisconsin-Madison, took the problem further with a chemical rather than biological approach.

Khorana’s group synthesised artificial RNA molecules of precisely defined nucleotide sequence — a technically formidable achievement — and used them to direct protein synthesis in cell-free systems. By systematically varying the sequences and observing which amino acids were incorporated, they deciphered the complete genetic code: all 64 codons and their corresponding amino acids, including the three “stop” codons that terminate protein synthesis. The work confirmed that the genetic code is universal — that the same codons specify the same amino acids in bacteria, plants, and animals. The Nobel Prize in Physiology or Medicine 1968 was shared by Khorana, Nirenberg, and Robert Holley for their complementary contributions to cracking the code.

Khorana did not stop at the Nobel. He moved to MIT in 1970 and continued pushing the boundaries of synthetic biology. In 1972 his group synthesised the first complete artificial gene — a yeast transfer RNA gene — nucleotide by nucleotide. In 1979 they synthesised a functional gene from scratch and expressed it in a living cell. These achievements laid the conceptual and technical foundations for gene synthesis, genetic engineering, and ultimately the entire biotechnology industry. He became a U.S. citizen in 1966 and received the National Medal of Science in 1987. He died in Concord, Massachusetts, on November 9, 2011, aged eighty-nine.

The arc of Khorana’s life is one of the most dramatic in the history of science: from a village with no school in colonial Punjab to MIT professor, from a boy taught to read under a tree to Nobel laureate and pioneer of the biotechnology revolution. The genetic code he deciphered is now used millions of times a day in every molecular biology laboratory in the world. Every genetic test, every gene therapy, every mRNA vaccine rests on the foundation his work constructed. The village of Raipur — now across the border in Pakistan — produced one of the scientists most responsible for the molecular basis of life as we now understand it.