Complementarity (molecular biology)

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On the left: nucleotides that form the DNA and their complementary. Between A and T there are two hydrogen bonds, while 3 are between C and G. On the right a DNA sequence and its complementary strand.

In molecular biology, complementarity is a property of double-stranded nucleic acids such as DNA and RNA as well as DNA:RNA duplexes. Each strand is complementary to the other in that the base pairs between them are non-covalently connected via two or three hydrogen bonds.

Since there is only one complementary base for any of the bases found in DNA and in RNA, one can reconstruct a complementary strand for any single strand. This is essential for DNA replication.

For example, the complementary strand of the DNA sequence

A G T C A T G

is

T C A G T A C

tRNAs exhibit wobble, in which the third base of their anticodon does not follow the strict complementarity rules.

[edit] See also

• Base pair