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Secondary structure is the set of interactions between bases, i.e., which parts of strands are bound to each other. In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand. The secondary structure is responsible for the shape that the ...
The two DNA strands are known as polynucleotides as they are composed of simpler monomeric units called nucleotides. [2] [3] Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group.
This nucleotide contains the five-carbon sugar deoxyribose (at center), a nucleobase called adenine (upper right), and one phosphate group (left). The deoxyribose sugar joined only to the nitrogenous base forms a Deoxyribonucleoside called deoxyadenosine, whereas the whole structure along with the phosphate group is a nucleotide, a constituent of DNA with the name deoxyadenosine monophosphate.
A nucleotide is an organic molecule consisting of a nitrogenous heterocyclic nucleobase (a purine or a pyrimidine), a pentose sugar (deoxyribose in DNA or ribose in RNA), and a phosphate or polyphosphate group.
Chemical structure of DNA, showing four nucleobase pairs produced by eight nucleotides: adenine (A) is joined to thymine (T), and guanine (G) is joined to cytosine (C). + This structure also shows the directionality of each of the two phosphate-deoxyribose backbones, or strands.
In molecular biology, two nucleotides on opposite complementary DNA or RNA strands that are connected via hydrogen bonds are called a base pair (often abbreviated bp). In the canonical Watson-Crick base pairing, adenine (A) forms a base pair with thymine (T) and guanine (G) forms one with cytosine (C) in DNA.
The nucleic acid notation currently in use was first formalized by the International Union of Pure and Applied Chemistry (IUPAC) in 1970. [1] This universally accepted notation uses the Roman characters G, C, A, and T, to represent the four nucleotides commonly found in deoxyribonucleic acids (DNA).
Nucleotides are heterocyclic compounds, that is, they contain at least two different chemical elements as members of its rings. [citation needed] Both RNA and DNA contain two major purine bases, adenine (A) and guanine (G), and two major pyrimidines. In both DNA and RNA, one of the pyrimidines is cytosine (C).