Complementarity (molecular biology)

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On the left: nucleotides that forms the DNA and their complementary. Between A and T there are 2 hydrogen bounds, while 3 are between C and G. On the right a DNA sequence and its complementary strand.

In genetics, a double-stranded DNA strand consists of two complementary strands of base pairs, which 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

A= adenine G= Guanine T= thymine C= cytosine U= uracil

Compliment and complementation have several different meanings in Biology, see Complement for other uses.

[edit] See also

• Watson and Crick Base Pairing
• Complementary DNA.