History of DNA

By Inarra Subazali

Gregor Mendel

In 1843 Gregor Mendel discovered the fundamental laws of inheritance. After studying plants, Mendel concluded that short plants off springs were short, while tall plants off springs were tall. The law of segregation, which is the first heredity law, is based on his observations plant's breeding. It states that the heredity or genes is found in pairs and that the paired gene is divided when the cell is divided. Also that the sperm and paired gene are present in half the eggs or sperm.

Frederick Griffith

In 1928 Frederick Griffith worked on a project that helped show others that DNA was the molecule of inheritance. Griffith used mice and injected a poison into the mouse killing it. After, he injected the non poison into a mouse and it lived. Griffith thought that the characteristic to the molecule. The passing on of inheritance is known as transformation.

Oswald Avery

Fourteen years later a scientist named Oswald Avery continued with Griffith’s experiment to see what the inheritance molecule was. In this experiment he destroyed the lipids, ribonucleic acids, carbohydrates, and proteins of the poison. Passing of inheritance still occurred. Next he destroyed the deoxyribonucleic acid. Because the transformation did not occur, Avery found the inheritance molecule, DNA.

Erwin Chargaff

In the 1940's Erwin Chargaff noticed a pattern in amounts of adeline, guanine, cytosine, and thymine. He found that adenine was equivalent to thymine and guanine was equivalent to cytosine.

Rosalind Franklin and Maurice Wilkins

In 1962 Rosalind Franklin and Maurice Wilkins made a crystal of the DNA molecule. They wanted to get DNA to crystallize so they could make an x-ray pattern, helping them to understand how DNA works. The two scientist succeeded and got an x-ray pattern. This pattern had a helix type shape.

James Watson and Francis Crick

In 1952 scientist James Watson and Francis Crick were putting together a model of DNA. After seeing Franklin and Wilkin's picture of the X-ray, they were able to make an accurate model, this model has stayed mostly the same up until now. THe model has a double helix with rungs, like a ladder, connecting these two strands. These ladders are known as bases of a nucleotide. They also discovered that the pairs, Thymine with Adenine and Guanine with Cytosine helped the DNA look uniformed. They also found that a hydrogen bond is formed between the pairs of these bases.