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The imino nitrogen can only serve as a donating atom in hydrogen bonding, but the amino nitrogen can also serve as a receiving atom. There is a preference for the amino and keto forms which is very crucial for the biological functioning of DNA as it provides a with the deoxyribose and it leads to the specificity of hydrogen bonding in base pairing and thus complementarity of the chains. Using an isolate thymine to illustrate the and the. The nitrogen atoms that are involved in forming tautomer appear as amino or imino groups and the oxygen atoms are either in keto or enol forms. Hydrogen atoms on some nitrogen and oxygen atom can undergo tautomeric shifts. The four types of bases are the two double-ringed purine base and and the two single-ringed pyrimidine bases and. In, the 3' carbon is out of the plane of the ribose ring. In this scene, which shows B DNA, the 2' carbon is out of the plane of the other members of the five membered ring. The of ribose is a main determinant of which of the Forms of DNA is present. The in DNA is composed of a bonded to the 5' of which is connected by a beta-glycosidic bond to a purine or a pyrimidine. This structure helps the DNA replicate itself during cell division and also for a single strand to serve as template during transcription. The structure of DNA is a : two complementary strands of polynucleotides that run in opposite directions and are held together by hydrogen bonds between them. Based on the works of Erwin Chargaff, James Watson, Francis Crick, Maurice Wilkins and Rosalind Franklin, the structure of DNA was discovered in the year 1953. ĭNA was first discovered by the German biochemist Frederich Miescher in the year 1869. 10 9 bases with around 20,000 genes on 23 chromosomes.RNA is used to make proteins by another process called translation. The expression of genetic information into proteins is a two-stage process wherein the sequence of nucleotides in DNA is converted to a molecule called Ribonucleic acid or RNA by a process called transcription. DNA stores genetic information as a sequence of nucleotides in special regions known as genes which are used to make proteins. The DNA in prokaryotes in generally circular and supercoiled without any histones. However in case of prokaryotes DNA is not enclosed in a nucleus or a membrane but is present in the cytoplasm. It is also found in cell structures called mitochondria. It contains the biological instructions for the development, survival and reproduction of organisms.ĭNA is found in the nucleus of a cell where it is packaged into a compact form called a chromosome with the help of several proteins known as histones.
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Deoxyribonucleic acid or DNA is a molecule which is the carrier of genetic information in nearly all the living organisms.