base pair

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base pair (b.p., bp),

the complex of two heterocyclic nucleic acid bases, one a pyrimidine and the other a purine, brought about by hydrogen bonding between the purine and the pyrimidine; base pairing is the essential element in the structure of DNA proposed by J. Watson and F. Crick in 1953; usually guanine is paired with cytosine (G·C), and adenine with thymine (A·T) or uracil (A·U).

base pair

n.
A pair of nitrogenous bases, consisting of a purine linked by hydrogen bonds to a pyrimidine, that connects the complementary strands of DNA or of hybrid molecules joining DNA and RNA. The base pairs are adenine-thymine and guanine-cytosine in DNA, and adenine-uracil and guanine-cytosine in RNA.

base pair

The structure formed between 2 complementary nitrogenous bases—purines and pyrimidines—which are hydrogen-bonded (guanine and cytosine share 3 hydrogen bonds; adenine and thymine share 2) to form double-stranded nucleic acids—DNA or RNA.

BPs are held together by weak hydrogen bonds; in double-stranded nucleic acids (DNA, RNA), purines (adenine and guanine) bond to their complementary opposites, pyrimidines (cytosine thymine, uracil)—under normal circumstances, adenine binds to thymine (DNA) or to uracil (RNA), and guanine binds to cytosine (DNA and RNA).

base pair

(bās pār)
The complex of two heterocyclic nucleic acid bases, one a pyrimidine and the other a purine, brought about by hydrogen bonding between the purine and the pyrimidine; base pairing is the essential element in the structure of DNA. Usually guanine is paired with cytosine (G·C), and adenine with thymine (A·T) or uracil (A·U). The sequence of the complementary bases in either strand of a two-stranded DNA molecule codes for amino acids used in the manufacture of proteins. Trios of bases (codons) specify each of 20 amino acids. During protein synthesis (translation), messenger RNA and ribosomes read the order of amino acids from strings of DNA to create protein chains, which are then released into the cell.

base pair

Two linked molecules, one a purine the other a pyrimidine, that lie across between the two strands of the DNA double helix. The bases are linked by easily-broken hydrogen bonds and the linkage occurs only in a particular, complementary, way-adenine with thymine and guanine with cytosine. This is the essence of DNA replication, which starts with the separation of a length of the two strands at bonds. In RNA, uracil replaces thymine and adenine links with it. Distance along a DNA sequence is measured as the number of base pairs.

base pair (bp)

in double-stranded NUCLEIC ACID molecules, a pair of complementary NUCLEOTIDES: in DNA, A-T and G-C; in RNA, A-U and G-C, with one nucleotide contributed from each strand of the DUPLEX. The pair of bases is held together by HYDROGEN BONDS. The length of a double-stranded nucleic acid molecule is measured in base pairs. See also COMPLEMENTARY BASE PAIRING.