History of DNA

By: Megan Coutoumanos

Gregor Mendel

He was a German in the 1800's who studied genetics. He discovered the basics of DNA. Like the Law of segregation (dominate and restive traits) and the Law of Independent Assortment (traits came from the parents to the offspring. This gave the future scientists somewhere to start and basic information to investigate deeper.

Frederick Griffith

Frederick Griffith was a British bacteriologist. In 1928 Griffith discovered that one of the 2 stains, on the bacteria streptococcus pneumoniae, that one has a sugar coat (smooth strain) and one without a sugar coat (rough strain). He also discovered that the s strain can cause pneumonia but the other does not cause diseases. He proved this by testing the bacteria on mice. This shows that DNA is changeable.

Oswald Avery

He was an American who studied molecular biology. Avery is known for discovering, in 1944, that when the r strain was exposed with the s strain then the r would transform into an s strain. He also saw that when the s strains were killed, they released their DNA and the r strains picked them up and became s strains themselves. This showed that DNA could be transported.

Erwin Chargaff

Chargaff was an Australian biochemist. He made amazing discoveries in 1950, like his C=G and T=A. He looked into how much adenine, guanine, thymine, and cytosine was in DNA in different organisms. He saw that the amount of thymine and adenine was similar and the amount of cytosine and guanine are similar. This shows that DNA is in all living things.

Maurice Wilkins

Maurice Wilkins was a British man who studied molecular biology and physics. In 1951 he created X-Ray diffraction. It is aiming X-Rays at a DNA molecule. This helped Rosalind Franklin get her research.

Rosalind Franklin

Rosalind Franklin was In 1951, she took a picture of DNA that affected all of the other scientists after her. She took a picture of DNA with x-Ray diffraction (aimed X-Rays at DNA). Her research showed that DNA is in a twisted ladder shape, otherwise known as a double helix. This is the structure for all organisms.