Watson and Crick By John Yogus February 27, 2004

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James Watson Young American Scientist Strong interest in discovering the structure of DNA. Earned his bachelors degree at age 19 and his PhD at 22

Francis Crick English scientist Worked at the Cavendish Laboratory

Watson and Crick In the early 1950s the race was on to discover the structure of DNA. Watson traveled to Cambridge to study with Crick.

Important Others Other prominent figures were trying to discover the structure of DNA. These included Linus Pauling and Rosalind Franklin. There was no connection between these people and Watson and Crick

Linus Pauling Pauling was an American chemist. Prior to Watson going to London, Pauling beat Cavendish scientists in discovering the structure of keratin.

Rosalind Franklin Franklin was an English scientist who worked at Kings College. She was an exemplary x-ray diffractionist.

True or False Pauling worked with Watson and Crick on the discovery of the double helix. TrueFalse TrueFalse

Working to Discovery The framework for Watson and Cricks work was set forth by earlier scientists such as –Frederick Griffith –Oswald Avery –Hershey and Chase

Watson and Crick In 1951, Watson sat in on a conference by Maurice Wilkins of Kings College London. He was using X-ray diffraction to study the structure of DNA.

Crick and Wilkins were good friends. Crick and Wilkins were good friends. However, Wilkins worked with Franklin and these two were on bad terms. However, Wilkins worked with Franklin and these two were on bad terms. Franklin was an accomplished crystallographer. Franklin was an accomplished crystallographer. She wouldnt share info with Watson and Crick She wouldnt share info with Watson and Crick

Watson and Crick Wilkins and Franklin worked at Kings College.

Watson and Crick Watson sat in on a seminar of Franklins. He did not take notes on her lecture. He erroneously began work on modeling the structure of DNA. These efforts proved fruitless.

Watson and Crick temporarily gave up on their work. Watson studied tobacco mosaic virus and Crick hemoglobin. Click the red arrow below to see pictures of the tobacco mosaic virus and hemoglobin.

At this point, Watson and Crick endorsed Franklin and Wilkins. At this point, Watson and Crick endorsed Franklin and Wilkins. Franklin discovered that DNA could take two forms, A and B. Franklin discovered that DNA could take two forms, A and B. Franklin and Wilkins fought over this and Franklin was awarded the A type and Wilkins the B type. Franklin and Wilkins fought over this and Franklin was awarded the A type and Wilkins the B type. Click the red button below to see A and B forms of DNA. Click the red button below to see A and B forms of DNA.

A and B DNA A is on the left and B is on the right.

Watson and Crick In the mean time, Watson and Cricks interest was still alive in DNA. In the mean time, Watson and Cricks interest was still alive in DNA. During their lapse, they tried to determine how Chargaffs rule played into the picture. During their lapse, they tried to determine how Chargaffs rule played into the picture.

Watson and Crick In December of 1952, it was suggested that Pauling had come up with the structure of DNA. Watson and Crick immediately knew this wasnt the case after examining Paulings model. Pauling suggested a triple helix.

However, this put pressure on the two to figure out the structure of DNA. Paulings model provided many clues that would help others in their search.

Watson went to London to warn Wilkins and Franklin. However, he and Franklin had a major fall out. Just then, Wilkins walked into the lab and rescued Watson.

As the two walked away, Wilkins showed Watson a different picture of a B DNA x-ray diffraction. As the two walked away, Wilkins showed Watson a different picture of a B DNA x-ray diffraction. It was Photograph 51. It was Photograph 51. A forms are on the left and B forms are on the right. A forms are on the left and B forms are on the right.

Watson and Crick At this point, Watson immediately knew the structure of DNA had to be a helix.

Watson raced back to his Cavendish Laboratory. Watson raced back to his Cavendish Laboratory. There, he and Crick immediately began building models of DNA. There, he and Crick immediately began building models of DNA.

Watson and Crick In February of 1953, Watson and Crick invited Wilkins and Franklin to lunch. In February of 1953, Watson and Crick invited Wilkins and Franklin to lunch. From this meeting, Watson and Crick obtained information that the strands of DNA run in opposite directions. From this meeting, Watson and Crick obtained information that the strands of DNA run in opposite directions.

Fast Fact Did you notice in the previous slide the letters A, T, G and C in the hexagons? They are symbols for the 4 nitrogenous bases used in DNA. They represent Adenine, Thymine, Guanine and Cytosine. Click on the names of the nitrogenous bases above to hear the correct pronunciation of their names. AdenineThymineGuanineCytosine AdenineThymineGuanineCytosine

Watson and Crick This information helped, but the two were still unsure how the nitrogenous bases paired up with each other. Then, Watson remembered Chargaffs rule. His rule was based on the data to the left.

Implementing Chargaffs rule, he concluded Adenine and Thymine were paired together. Implementing Chargaffs rule, he concluded Adenine and Thymine were paired together. Similarly, Guanine and Cytosine were also paired together. Similarly, Guanine and Cytosine were also paired together.

Watson and Crick This configuration also suggested a mechanism for replication of DNA. This configuration also suggested a mechanism for replication of DNA.

Watson and Crick On February 28, 1953 Watson and Crick walked into the Eagle pub in London and announced they had found the secret of life. On February 28, 1953 Watson and Crick walked into the Eagle pub in London and announced they had found the secret of life.

Question Who were among the first people that Watson and Crick shared their discovery with? A) The International Genetic Society The International Genetic Society The International Genetic Society B) London DNA Institute London DNA Institute London DNA Institute C) Biology faculty at Kings College Biology faculty at Kings College Biology faculty at Kings College D) Cavendish Historic Society Cavendish Historic Society Cavendish Historic Society E) Drinking buddies at the local pub Drinking buddies at the local pub Drinking buddies at the local pub

Watson and Crick This is what Watson and Crick discovered. Click on the picture to see this in animation.

Watson and Crick Watson and Crick published a one page letter in Nature on April 25, 1953 that informed the public of their findings. Watson and Crick published a one page letter in Nature on April 25, 1953 that informed the public of their findings.

Watson and Crick Watson and Crick, along with Wilkins, were awarded the Noble Prize in 1962 for their efforts.

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Acknowledgements Time, February 17, 2003 Watsoncrombie and Crick Ohio State University Stanford University The bicameral mind BBC News SKonline University of Georgia

Acknowledgements Memorial University of Newfoundland The Bacculaerate School for Global Education Citrus College University of Pennsylvania University of Miami John Cash DT Media Limited Purdue University Kings College

Correct The answer is false. Pauling did not work with Watson and Trick. Click here to continue Click here to continue

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Correct Watson and Crick walked into the Eagle Pub on the day of their discovery and announced that they had found the structure of life. Click here to continue with the show Click here to continue with the show

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