Restriction sites, or restriction recognition sites, are particular sequences of nucleotides that are recognized by restriction enzymes as sites to cut the DNA molecule. The sites are generally palindromic, and a particular enzyme may cut between two nucleotides within its recognition site, or somewhere nearby. For example, the common restriction enzyme EcoRI recognizes the sequence GAATTC and cuts between the G and the A on both the top and bottom strands, leaving an overhang (an end-portion of a DNA strand with no attached complement) on each end, of AATT. This overhang can then be used to ligate in (see DNA ligase) a piece of DNA with a complementary overhang (another EcoRI-cut piece, for example). A nucleotide is a monomer or the structural unit of nucleotide chains forming nucleic acids as RNA and DNA. A nucleotide consists of a heterocyclic nucleobase, a pentose sugar, and a phosphate or polyphosphate group. ... A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the phosphate backbones of the double helix without damaging the bases. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ... A palindrome is a word, phrase, number or any other sequence of units (like a strand of DNA) which has the property of reading the same in either direction (the adjustment of spaces between letters is generally permitted). ... In molecular biology, DNA ligase is a particular type of ligase (EC 6. ...
Restriction enzymes are site-specific endonucleases; that is, they cut DNA molecules only at sites where a specific sequence of bases occurs that the enzyme recognizes.
Restriction endonucleases are enzymes that cleave both strands of double stranded DNA after recognizing specific nucleotide sequences on the molecule.
Restriction enzymes "restrict" the host range of bacteriophage to strains of bacteria containing the identical set of restriction/modification genes present in the strain in which the virus was originally replicated.
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