Complementarity

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

5' A G T C A T G 3'

is

3' T C A G T A C 5'

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

See also

• Base pair