The next critical discovery was made by Russian biochemist Phoebus Levene. Miescher was right, but it took decades for the scientific community to fully appreciate his insights. He did not know what it was, but he suspected that it could be biologically important.

In the process of extracting protein from white blood cells, Miescher found an unexpected substance that had relatively high phosphorus content. The story of the discovery of DNA structure begins in 1869 when Swiss scientist Friedrich Miescher discovered a substance he called “nuclein”. The Discovery of DNA Structure: A Brief History Relatively few proteins bind to DNA via the minor groove. The minor groove, by contrast, occurs where the sugar-phosphate backbones are close together. This space grants access to DNA-binding proteins, such as transcription factors. The major groove occurs where the sugar-phosphate backbones are relatively far apart. Instead, there are regularly occurring grooves in the structure. However, the double helix is not perfectly symmetrical. The two strands of the DNA molecule are tightly wound into a spring-like structure called a double helix. Without this arrangement, the nucleotides would be in the wrong position to form hydrogen bonds between strands. This hydrogen bonding is made possible by the antiparallel arrangement of the two DNA strands, in which the 5’ and 3’ ends of the strands are oriented in opposite directions. The two strands of nucleotides are held together by hydrogen bonds, in which the adenines in one strand pair with thymines at the same position in the other strand, and the cytosines in one strand pair with guanines in the same position in the other strand. Cytosine and thymine belong to a group of single-ringed structures called pyrimidines.Īdjacent nucleotides in the same strand are covalently linked by phosphodiester bonds. Adenine and guanine are members of a larger class of chemicals called purines that all contain two-ringed structures. DNA Structure in DetailĮach strand of DNA consists of subunits called nucleotides that contain the sugar deoxyribose, a phosphate group, and one of four nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The discovery of the structure of DNA occurred incrementally over nearly a century, representing one of the most famous and captivating stories in the history of science. DNA is composed of two strands of nucleotides that wind around each other to form a double helix. Deoxyribonucleic acid, or DNA, is the genetic material responsible for passing traits from generation to generation in all organisms and most viruses.

Double helix dna