A Nobel Prize medal honoring the discovery of DNA's twisted ladder shape was sold at auction on April 11 in New York for more than $2 million.

Francis Crick was one of three men awarded the Nobel Prize in Physiology or Medicine for the 1953 discovery of the DNA molecule's double-helix structure. Sixty years later, Crick's medal and accompanying diploma fetched a winning bid of $1.9 million at Heritage Auctions. (The final price, including buyer's fees, was $2,270,500).

At a separate auction yesterday, a letter penned by Crick set the world record for any letter ever sold at auction. An anonymous bidder paid just over $6 million for the note Crick wrote to his 12-year-old son that explained the DNA discovery and was signed "lots of love, Daddy."

A chunk of the proceeds from this week's sales are set to benefit research institutions in the United States and the United Kingdom. Crick's family and Heritage Auctions plan to donate a portion of today's earnings to The Francis Crick Institute, a medical research institute, scheduled to open in London in 2015. Half of the proceeds from yesterday's letter auction are set go to the Salk Institute in California, where Crick, who died in 2004, studied consciousness later in his career. [See Photos of Crick's Medal & Other Auction Items]

There was little precedent for today's sale. Heritage Auctions had valued the Nobel medal and diploma at $500,000 — a fourth of what it raked in. Nobel medals appear to have changed hands publicly in only a couple of instances and none had been publicly auctioned off before. Crick's medal might be considered particularly valuable as it honored one of the most important scientific discoveries of the 20th century.

As early as the later 1800s, scientists knew that the DNA molecule existed, but not what it looked like or its true function. The discovery of DNA's double helix structure was key to understanding how the molecule worked as a code for genes. Crick's granddaughter told LiveScience earlier this year that the family hopes to see the Nobel medal displayed publicly after its sale.

Other Crick-related mementos went under the hammer today. His award check with his endorsement on the back sold for $77,675; the scientist's lab coat went for $8,962; his gardening journals sold for $10,755; and a set of his nautical logs and books snagged $1,792. A bidder also paid $4,182 for Crick's personal copy of Charles Darwin's "The Zoology of the Voyage of H.M.S. Beagle."

At yesterday's sale at Christie's auction house in New York, an anonymous buyer purchased Crick's seven-page handwritten note to his son with a $5.3 million bid over the phone. Buyer's premium included, the final price tag for the "Secret of Life" letter came in at $6,059,750.

The sale far exceeded expectations. Christie's had valued the letter at $1-2 million, comparing its value to a letter Albert Einstein wrote to President Franklin D. Roosevelt warning about the potential of nuclear weapons. Christie's sold that letter in 2002 for just over $2 million. 

Dated March 19, 1953, the letter contains diagrams that outline the scientists' model for how "des-oxy-ribose-nucleic-acid (read it carefully)" replicates and encodes instructions for the development and function of living things.

"In other words we think we have found the basic copying mechanism by which life comes from life," Crick wrote to his son, Michael, who was at boarding school at the time. [See Images of Crick's 'Secret of Life' Letter]

As legend has it, when James Watson and Crick made their discovery on Feb. 28, 1953, Crick announced inside a local Cambridge pub called the Eagle, "We have discovered the secret of life." Their findings wouldn't be published in the journal Nature until two months later, and the note to Michael is likely one of the first written explanations of the discovery.

"As far as we know this is the first public description of these ideas that have become the keystone of molecular biology and which have spawned a whole new industry and generations of follow on discovery," Michael Crick wrote in Christie's catalogue.

One of Crick's notebooks was sold yesterday at Christie's for $21,250, and drawing of Crick made by his wife, Odile Crick, an artist who drew the double helix for her husband and Watson, was auctioned off for $17,500.

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