Who deduced the double-helical structure of DNA?

Watson and Francis Crick

The correct answer is option 4. Watson and Francis Crick.

The discovery of the double-helical structure of DNA is one of the most significant achievements in the history of molecular biology. It was primarily the work of James Watson and Francis Crick, with important contributions from Rosalind Franklin and Maurice Wilkins.

Here is a detailed explanation:

1. Background:

Before Watson and Crick, scientists knew that genetic information was stored in the form of DNA, but the structure of DNA was unknown. Linus Pauling had proposed a triple helix structure for DNA, but this was later proven to be incorrect.

2. Contributions of Rosalind Franklin:

Rosalind Franklin, an X-ray crystallographer, played a crucial role in providing key experimental data. She used X-ray diffraction to study the structure of DNA fibers. Franklin's images, particularly Photo 51, provided critical information about the helical nature of DNA and the distance between the helical turns.

3. Watson and Crick's Model:

In 1953, James Watson and Francis Crick, at the University of Cambridge, proposed a model for the structure of DNA based on their interpretation of Franklin's X-ray diffraction images and additional insights. They built physical models of the DNA molecule, attempting to find a structure that fit the observed data.

Watson and Crick's model proposed a double helix: two long strands of DNA running in opposite directions, with the famous Watson-Crick base pairs (adenine with thymine and guanine with cytosine) forming the rungs of the helical ladder. The hydrogen bonds between these base pairs provided the specificity in the pairing.

The double helix structure elegantly explained how genetic information could be stored and replicated. The complementary base pairing allowed for the faithful transmission of genetic information during cell division.

4. Publication and Recognition:Watson and

Crick published their model of DNA structure in the scientific journal Nature in April 1953. The paper, titled "Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid," is one of the most famous scientific papers ever published.

Their model was quickly accepted by the scientific community, and it laid the foundation for understanding how genetic information is stored and transmitted. The double helix became an iconic representation of DNA.

5. Legacy:

Watson, Crick, and Wilkins were awarded the Nobel Prize in Physiology or Medicine in 1962 for their discoveries related to the molecular structure of nucleic acids. Unfortunately, Rosalind Franklin had passed away by then and, as per Nobel rules, was not eligible for posthumous awards.

In summary, the deducing of the double-helical structure of DNA was a collaborative effort with key contributions from Watson, Crick, and Franklin, and it revolutionized our understanding of genetics and laid the groundwork for subsequent advances in molecular biology.