Question

How did Francis Crick and James Watson try to understand the structure of DNA?

Answer 1

Francis Crick and James Watson determined DNA's structure using X-ray crystallography data, mainly from Rosalind Franklin's work, along with Chargaff's rules on nucleotide pairing. They proposed the double helix model and shared the Nobel Prize with Maurice Wilkins, while Franklin was notably absent from the award due to her earlier demise.

Step-by-step explanation:

Understanding the Structure of DNA

In the 1950s, Francis Crick and James Watson collaborated at the University of Cambridge, England, to elucidate the structure of DNA. Their approach integrated data from various sources, notably X-ray crystallography data from Rosalind Franklin's work in Maurice Wilkins' laboratory. This technique was instrumental in revealing the helical structure of DNA. Crick and Watson also leveraged Chargaff's rules, which elucidated that DNA's nucleotides are paired in a specific manner - adenine (A) with thymine (T) and cytosine (C) with guanine (G). In 1962, Watson, Crick, and Wilkins received the Nobel Prize in Medicine for their groundbreaking discovery of DNA's double helix configuration. However, Franklin had passed away by that time and was not posthumously honored with a Nobel Prize.

It's crucial to acknowledge the collaborative nature of this scientific breakthrough, as the combined efforts and findings of various researchers paved the way for Watson and Crick to build their model of the DNA double helix. The final structure they proposed showcased two strands of nucleotides twisting into a double helix, with the sugar and phosphate groups on the exterior and the paired bases on the interior, connecting the two strands.

Answer 2

Francis Crick and James Watson, along with contributions from Rosalind Franklin and Maurice Wilkins, are credited with determining the structure of DNA. Their work was primarily based on a model-building approach, combining existing experimental data with theoretical insights. Here's a brief overview of their methods:

1. x-ray Crystallography Data:

Rosalind Franklin, a biophysicist, used X-ray crystallography to study the structure of DNA. She produced high-quality X-ray diffraction images of DNA fibers, which showed a distinct X-shaped pattern.Maurice Wilkins also contributed X-ray diffraction images of DNA.

2. Base Pairing:

Chargaff's rules, established by biochemist Erwin Chargaff, provided crucial information about the relative abundance of nucleotides in DNA. This information hinted at the complementary base pairing in DNA (A with T, and G with C).

3. Model Building:

Crick and Watson used cardboard cutouts representing the nucleotide bases and metal model-building kits to visualize possible three-dimensional structures of DNA.They proposed a model in which two DNA strands are twisted into a double helix, with the sugar-phosphate backbones on the outside and the nitrogenous bases on the inside.

4. Base Pairing and Hydrogen Bonds:

They incorporated Chargaff's base-pairing rules into their model, ensuring that adenine (A) always paired with thymine (T) and guanine (G) with cytosine (C).Hydrogen bonds were crucial in stabilizing these base pairs.

5. Double Helix Structure:

Crick and Watson's final model, published in the journal Nature in 1953, depicted DNA as a double helix with a uniform diameter.The antiparallel nature of the two DNA strands and the complementary base pairing explained how genetic information could be accurately replicated.

Their model of the DNA structure laid the foundation for understanding the mechanism of DNA replication and became a cornerstone in the field of molecular biology. It provided profound insights into how genetic information is stored and transmitted in living organisms.