نانوساختار‌های DNA

نانوساختار‌های DNA

اسلاید 1: DNA as a NanomaterialPresentation: Sajjad BabaeiPh.D. student of Nano-biotechnology, School of Sciences, Razi Uni. Kermanshah, IranLecture: applications of Nano-biotechnology

اسلاید 2: 1. IntroductionDNA is a biomacromolecule composed of sugar, phosphate and organic bases. It has unique and interesting features.2

اسلاید 3: 1-1.DNA’s structure 3This molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms and many viruses.DNA is a long polymer made from repeating units called nucleotides. two helical chains, bound to each other by hydrogen bonds. The pair of chains has a radius of 10 ångströms (1.0 nanometre). The backbone of the DNA strand is made from alternating phosphate and sugar(2-deoxyribose) residues. The sugars are joined together by phosphate groups that form phosphodiester bonds.(which are known as the 3′ and 5′ carbons).The four bases found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T). These four bases are attached to the sugar-phosphate to form the complete nucleotideThe DNA double helix is stabilized primarily by two forces: hydrogen bonds between nucleotides and base-stacking interactions among aromatic nucleobases.

اسلاید 4: 4

اسلاید 5: Hydrogen Bonds5

اسلاید 6: Major forms of hydrogen bonds in the DNA structure6In these various forms, the atoms involved in the H-bond are different.Therefore, it changes the states of syn and anti

اسلاید 7: Base-stacking InteractionsWhen this interactions occurs, that two aromatic rings, such as two plates, are placed nearby on each other. Interactive periodic rise and fall in electron cloud, creates a force between the rings.When the electron cloud is thin around one of the ring and a positive charge is created, in that moment, the other one (another ring), has a thick electron cloud which gives it a negative charge. Then a link between the positive and negative charges will be created.In the next moment, the position of positive and negative areas is changed. as the result, the connection of the rings will be continuous. The reason for this is the harmony of electron cloud rise and fall times in the adjacent rings.This interaction can be flexible and take on the different structural states7

اسلاید 8: Base-stacking Interactions8

اسلاید 9: DNA has different types forms : A ,B, C, D, Z, H, ICreating these forms of DNA depends on the environmental conditions and the presence of some ions and moleculesThe presence of these forms is highly depends on humidityDepending on the environmental conditions, these forms can be transformed into each otherFor example : B-DNA in an environment with the following features, can change to Z-form :high concentration of saltadding bromine or methyl to cytosinein the presence of regulatory proteins9

اسلاید 10: 10

اسلاید 11: Structural comparison of different types of DNA11