![]() Ĭomplementarity of DNA strands in a double helix make it possible to use one strand as a template to construct the other. Hydrogen bonding between the nucleobases also stabilizes the DNA double helix. G ≡ C, takes up roughly the same space, thereby enabling a twisted DNA double helix formation without any spatial distortions. Nucleic AcidĪdenine(A), thymine(T), guanine(G), cytosine(C)Īdenine(A), uracil(U), guanine(G), cytosine(C)Ī complementary strand of DNA or RNA may be constructed based on nucleobase complementarity. DNA strands are oriented in opposite directions, they are said to be antiparallel. All other configurations between nucleobases would hinder double helix formation. The base complement A = T shares two hydrogen bonds, while the base pair G ≡ C has three hydrogen bonds. In nucleic acid, nucleobases are held together by hydrogen bonding, which only works efficiently between adenine and thymine and between guanine and cytosine. Both types of molecules complement each other and can only base pair with the opposing type of nucleobase. Adenine and guanine are purines, while thymine, cytosine and uracil are pyrimidines. Right: two complementary strands of DNA.Ĭomplementarity is achieved by distinct interactions between nucleobases: adenine, thymine ( uracil in RNA), guanine and cytosine. Between A and T there are two hydrogen bonds, while there are three between C and G. Left: the nucleotide base pairs that can form in double-stranded DNA. While most complementarity is seen between two separate strings of DNA or RNA, it is also possible for a sequence to have internal complementarity resulting in the sequence binding to itself in a folded configuration. In biotechnology, the principle of base pair complementarity allows the generation of DNA hybrids between RNA and DNA, and opens the door to modern tools such as cDNA libraries. Furthermore, various DNA repair functions as well as regulatory functions are based on base pair complementarity. The degree of complementarity between two nucleic acid strands may vary, from complete complementarity (each nucleotide is across from its opposite) to no complementarity (each nucleotide is not across from its opposite) and determines the stability of the sequences to be together. ![]() This complementary base pairing allows cells to copy information from one generation to another and even find and repair damage to the information stored in the sequences. In nature complementarity is the base principle of DNA replication and transcription as it is a property shared between two DNA or RNA sequences, such that when they are aligned antiparallel to each other, the nucleotide bases at each position in the sequences will be complementary, much like looking in the mirror and seeing the reverse of things. In molecular biology, complementarity describes a relationship between two structures each following the lock-and-key principle. Match up between two DNA bases (adenine and thymine) showing hydrogen bonds (dashed lines) holding them together
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