DNA Structure Watson Crick and Franklin

Описание: The Discovery of the Double Helix
The structure of DNA was one of the greatest scientific mysteries of the twentieth century. Scientists knew that DNA carried genetic information but did not understand how it was built. James Watson and Francis Crick worked together at Cambridge University to solve this puzzle. They used cardboard models to try and fit the different chemical pieces together. Their goal was to create a physical representation that explained how life copies itself.
The Contribution of Rosalind Franklin
Rosalind Franklin was a brilliant chemist who specialized in taking X-ray images of molecules. She used a technique called X-ray crystallography to capture high-resolution pictures of DNA fibers. Her most famous image is known as Photo 51 and it provided essential clues about the shape of the molecule. Although she did not get full credit at the time, her data was vital for the final discovery. She proved that the phosphate groups were on the outside of the structure.
Maurice Wilkins and the Lab Work
Maurice Wilkins worked at King’s College London and was a colleague of Rosalind Franklin. He was also interested in the structure of DNA and had been studying it using X-rays for several years. Wilkins showed Franklin’s X-ray data to Watson without her direct permission or knowledge. This information helped Watson and Crick realize that DNA was shaped like a spiral. Wilkins eventually shared the Nobel Prize with Watson and Crick for this work.
The Basic Shape of DNA
DNA is shaped like a long twisted ladder which scientists call a double helix. The two sides of the ladder are made of sugar and phosphate molecules. These two strands run in opposite directions to each other like lanes on a highway. The twisting shape allows a very long molecule to be packed into a tiny space inside a cell. This structure is very stable and protects the genetic code stored inside.
The Chemical Building Blocks
DNA is made up of smaller units called nucleotides that repeat over and over again. Each nucleotide consists of three parts including a phosphate group and a sugar molecule. The third part is a nitrogen base which carries the actual genetic information. There are four different types of bases found in every living thing on Earth. These building blocks link together in long chains to form the backbone of the molecule.
The Four Nitrogen Bases
The four nitrogen bases in DNA are named adenine, thymine, cytosine, and guanine. Scientists usually refer to these bases by their first letters which are A, T, C, and G. These bases act like a biological alphabet to write the instructions for an organism. The specific order of these letters determines the traits of a person or a plant. Every living creature has a unique sequence of these four chemical bases.