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Business News/ Companies / People/  People behind the DNA
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People behind the DNA

Francis Harry Compton Crick and James Watson effectively founded the discipline of molecular biology

Francis Harry Compton Crick, co-discoverer of the structure of DNA.Photo: AFP (AFP)Premium
Francis Harry Compton Crick, co-discoverer of the structure of DNA.Photo: AFP
(AFP)

New Delhi: The late Francis Harry Compton Crick, co-discoverer of the structure of DNA, spent his Nobel prize money on building a new bathroom. “That’s one of the funniest things he told me," said Pushpa Mitra Bhargava, molecular biologist and longtime friend. “But that’s just him being brilliant and eccentric."

Sixty years before, in 1953, Crick and fellow biologist James Watson at the University of Cambridge published a paper in the British journal Nature that described the molecular structure of deoxyribonucleic acid, or DNA, and effectively founded the discipline of molecular biology.

Until that year, scientists had spent little over half a century fishing about for the biological basis of inheritance, or how attributes such as height and skin colour are passed on over generations. Though they had found the gooey DNA way back in 1868, it was only around 1943 that several researchers, working quite independently of one another, could show that DNA was a genetic material: it was somehow able to copy itself and thereby give instructions to form proteins and the different kinds of cells that made up amoeba all the way to blue whales.

Several scientists had come extremely close to discovering the structure of DNA. However, Watson and Crick trumped them because they not only intuitively guessed a plausible shape for this molecule but also hinted at the precise mechanism by which DNA could initiate and direct the reproduction process.

Their masterstroke, say experts familiar with the history of DNA, lay in a small paragraph, almost at the end of the paper that read, “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material."

As per this plan, the DNA molecule is made up of two long strands of sugar and phosphate. On them are festooned nitrogenous compounds, or bases that come in four varieties: adenine, thymine, guanine and cytosine.

Crick and Watson found out that the adenine always bonds with thiamine and guanine to cytosine and this bonding made the two strands look like a helix, or akin to a ladder with its handrailings spiralling upwards.

When it needs to copy itself, DNA is first “unzipped" along the middle. Special kinds of enzymes—akin to scissors and glue—do these jobs and each of the strands bind with another pair of unzipped DNA molecules. Other enzymes also proofread the results to find and correct any mistakes in the copying process. After the doubling, this gives rise to two exact copies of the original DNA molecule. Experts hailed the mechanism as ingenious. Crick, said Bhargava, told him that the “process was so beautiful and therefore had to be true".

The elegance of the model was slow to catch on with the contemporaries of Crick and Watson, said Samir Brahmachari, director general of the Council of Scientific and Industrial Research (CSIR) and a biologist who also worked on the structure of DNA. “But within nine years, they had won the Nobel Prize. Their idea was, thus, established beyond doubt," he added.

So-called genome-wide studies that permit the comparison of genomes between different populations and, thus, look for disease-causing genes are now possible at an unprecedented level of clarity. By comparing the gene expression patterns of model animals such as mice and rats under different environmental conditions, scientists can pinpoint chromosome regions that have their equivalents in the human genome and, thus, begin to understand the role that the environment plays in complex diseases such as hypertension.

Combined with Charles Darwin’s seminal idea that all living organisms evolved from a single common ancestor billions of years ago, the nature and replication patterns of DNA also shed an enormous amount of light on our understanding of evolution. Insights, such as the ones that humans shared 99% of their genes with chimpanzees and about a third with bacteria, wouldn’t have been possible without realizing the process by which DNA replicates.

Veteran molecular biologists say that, following the discovery by Watson and Crick, Indian researchers were quick to chart out independent lines of inquiry into the implications of the structure of DNA. Only recently have the commercial benefits of such research become evident.

“India had a strong research base in biophysics," said M. Vijayan, a molecular biologist at the Indian Institute of Science. “In fact, there was a raging argument between Crick and the late G.N. Ramachandran (GNR), on the structure of collagen."

Collagen is among the basic building materials of the plant kingdom and it ultimately turned out that Ramachandran, who’d argued for a triple helical structure for collagen, was right. “Sadly, there were no Nobel Prizes for GNR," said Vijayan.

Several students of Ramachandran and their students, in turn, were able to build up considerable expertise in the field and in 2009, India joined an elite group of six countries that have successfully decoded the human genome.

The discovery, which was announced by CSIR, will bring pharmaceutical companies a step closer to designing drugs accounting for the specific characteristics of the Indian physiology.

The US, the UK, China, Canada and South Korea are the five other countries to decipher the genetic code.

Some Indian companies have already begun offering commercial services that claim to map people’s genes to look for early signs of diseases, including cancer.

As Mint reported in 2011, Acton Biotech (India) Pvt. Ltd, a Pune-based biotechnology start-up, had begun selling genome scanning services at 20,000 a test.

A blood test and a month’s analysis would let people know their propensity to a range of nearly 100 diseases and disorders, including diabetes, asthma, hypertension, arthritis, obesity and even infertility.

“All of these diseases have a strong hereditary component," said Sandeep Saxena, founder and CEO. “What we’re offering is probability estimates of acquiring a disease within a certain number of years. Several conditions may be hereditary but can be managed if we discover them early and take adequate precautions."

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Published: 17 Jun 2013, 10:51 PM IST
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