Why does DNA look like a spiral

Discovery of the double helix Deciphering the structure of DNA

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In 1953, the molecular biologists James Watson and Francis Crick deciphered the double helix structure of DNA. Their discovery was the basis for further genetic research and techniques such as CRISPR.

Status: 02/08/2021

It has been known for decades that the structure of DNA resembles a double helix, an elegantly twisted rope ladder. James Watson and Francis Crick found it out in 1953. Three years earlier, the American molecular biologist Watson set out to decipher the structure of the genetic material deoxyribonucleic acid (DNA).

Watson started studying at the age of 15

April 25: World DNA Day

The date is intended to commemorate the day in 1953 when James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin, along with other colleagues, published their papers on the structure of DNA. The day of action was launched by the US government in 2003 to educate people about genetics and genomics.

Watson was born on April 6, 1928 in Chicago, where he also spent his childhood. At the age of 15 he began studying zoology at the University of Chicago. After receiving his doctorate in zoology in 1950, he continued to devote himself to his specialty: genetics. He traveled to Copenhagen on a scholarship. He met the New Zealand biophysicist Maurice Wilkins, who examined DNA by X-ray analysis - an encounter that was to be groundbreaking.

DNS models with assistance from Wilkins and Franklin

Nobel laureate in medicine for deciphering the structure of DNA: Francis Crick

Afterwards Watson worked in the "Cavenish Laboratory" of the British University of Cambridge with Nobel laureate Sir Lawrence Bragg, a pioneer of X-ray structure analysis. Here he made friends with the English physicist Francis Crick, also an expert in X-ray structure analysis. The two designed different models of DNA using the research results and X-ray structural data of Maurice Wilkins and his colleague Rosalind Franklin.

Watson and Crick with a double helix model

With the help of cardboard models, Watson and Crick tried to find out the spatial structure of the protein building blocks. They arranged their cardboard models spatially taking into account the chemical bridges and were given the structure of a double helix. The double helix consists of two strands wound around each other, which are connected to each other by bases arranged in pairs.

At that time Crick wrote his son Michael a letter in which he reported an "exciting discovery" and roughly outlined the structure of the DNA: threads made of phosphorus and sugar, between which the bases adenine (A) and thymine (T) as well as guanine ( G) and cytosine (C) combine in pairs like steps - like a rope ladder. One month later, on April 25, 1953, the researchers published their find on just two short pages in the journal "Nature".

Double helix receives Nobel Prize in Medicine

In 1962, James Watson and Francis Crick, along with Maurice Wilkins, received the Nobel Prize in Medicine. Rosalind Franklin was not recognized. Watson never publicly recognized her research achievements, which earned him a lot of criticism. In 1961 Watson took over a professorship at Harvard University, and in 1968 he became director of the "Cold Spring Harbor Laboratory" (CSHL) in New York. There he carried out cutting-edge research in molecular biology and wrote his book "The Double Helix". In 2007 Watson announced his resignation from the chancellery at the CHSL. Again and again criticism of him was loud because he is said to have expressed himself disparagingly towards blacks.

Lack of money and recognition

Highest recognition for services in medical research: the Nobel Prize medal

In 2014, Watson auctioned his Nobel Prize for lack of money. The auction raised $ 4.1 million. The buyer, a Russian billionaire, gave him the money - and the medal back. With this noble gesture he wanted to pay tribute to the impetus that the discovery of the double helix gave to cancer research, it is said.

Pioneer of genetic research

In fact, genetic research and gene therapy have only become possible when the structure of the DNA carrier is understood. Certain sections of this long series of base pairs, the genes, contain the information for specific characteristics. And mutations in these genes - such as bases that no longer fit together after the helix has been replicated - can, for example, promote cancer. From this knowledge, models for researching tumors and their treatment have emerged, such as the "cancer mouse", in which doctors implant human cancer genes into mice. And also genome editing and the much discussed, cheap and targeted technique for gene modification, the gene scissors CRISPR-Cas9, would hardly be conceivable without the fundamental findings of Watson and Crick.

  • "Milestones in Science and Technology: James Watson, Francis Crick, and Molecular Genetics": in "Schulfernsehen", ARD-alpha, on March 27th, 2017, at 1:45 pm