Discovery and Structure of DNA Sample Clauses

Discovery and Structure of DNA. ‌ Xxxxxx Xxxxxx first described heritability from breeding experiments with peas. In 1865 he discovered, that the different phenotypes of pea flowers can be ex- plained by specific ratio laws [59]. To this date, these laws are called and used as the “Mendelian laws”. The first isolation of DNA was by Xxxxxxxxx Xxxxxxxx in Tübingen, but at the time he failed to realize the importance of his discovery. In 1909 Xxxxxxx Xxxxxxxxx described one unit of heredity with the word gene. In 1953 the double-helix structure of DNA was revealed by Xxxxxx and Xxxxx [94]. DNA consists of four bases, connected by a sugar-phosphate backbone. The atoms are connected from 5’C atom to 3’C of the base, which gives the DNA strand its direc- tion (from 5’ to 3’). These bases, called nucleotides, build up two complementary linearly composed strands, which form a double helix. Two nucleotides respectively form hydrogen bonds, which stabilize the double helix. The four nucleotides are Adenine, Thymine, Guanine and Cytosine. A and T can bind to each other by form- Figure 1.1: Double helix structure of the DNA. The double helix is built up by linearly linked nucleotides - connected by a sugar-phosphate backbone. Hydrogen-bonds form only between A and T and between G and C. U.S. National Library of Medicine [89] ing two hydrogen bonds. Therefore, A and T are said to be complementary. G and C are also complementary: they form three hydrogen bonds. This complementary strand is called complementary DNA (cDNA). When two fitting cDNA strands bind to each other they form a double helix, mentioned above. The binding of two com- plementary strands is called hybridisation, where the complementary strands are also directionally complementary [97]. Inside the cell, DNA is always present in double helix form. Figure 1.1 depicts the double helix form with its backbone and nucleotides [98]. Xxxxx et al. [17] describe the transcription from DNA to RNA and the triplet coded translation from RNA to protein. Xxxxxx et al. [73] described the first DNA sequencing techniques. This means reading the information written in the DNA molecules of organisms as the four nucleotides. The next years revealed many different properties of DNA. The first microarray technologies were developed in the 1980s, enabling gene expression quantification utilising RNA molecule counts. We use the RNA count as a proxy of protein activity, by assumption. The first full sequenced human genome was published in 2001 by Xxxxxx et al. ...