| gaylus-site | <chemical> A yellowish white, translucent mineral, consisting of the carbonates of lime and soda, with water. Origin: Named after Gay-Lussac, the French chemist. (20 Mar 1998) |
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| receptor site | Point of attachment of viruses, hormones, or other activators to cell membranes. (05 Mar 2000) |
| catalytic site | <chemistry> The site on an enzyme where the substrate or substrates (the reactants of a chemical or biochemical reaction) attach in order to convert to the product or products of the reaction, at a much higher speed than the substrate would need to convert to the product alone. (16 Mar 1998) |
| replication site | The in vivo site on DNA of DNA replication. (05 Mar 2000) |
| restriction enzyme cutting site | <molecular biology> A specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (for example, every several hundred basepairs), others much less frequently (rare-cutter, for example, every 10,000 base pairs). (10 Mar 1998) |
| restriction site | A sequence in DNA that can be recognised and cut by a specific restriction enzyme. (12 Dec 1998) |
| restriction-site polymorphism | DNA polymorphism in which the sequence of one form of the polymorphism contains a recognition site for a particular endonuclease, but the sequence of the other form lacks such a site. (05 Mar 2000) |
| chi site | <molecular biology> Short, active sequences of DNA which strongly encourages crossing over of chromosomes to occur at that site. These sites become chiasmata more often than other sites. (05 Jan 1998) |
| ribosome binding site | The region of a messenger RNA molecule that binds the ribosome to initiate translation. (09 Oct 1997) |
| cleavage site | A sequence in DNA that can be recognised and cut by a specific restriction enzyme. (12 Dec 1998) |
| combining site | <biochemistry, immunology> Any region of a molecule that binds or reacts with a given compound. Especially of the region of immunoglobulin that combines with the determinant of an appropriate antigen. (09 Jan 1998) |
| placental site trophoblastic tumour | A tumour usually arising in the uterus of parous women during reproductive years. Histologically, the tumour consists of a predominance of intermediate trophoblastic cells with fibrinoid material and vascular invasion. (05 Mar 2000) |
| Con A binding site | <biochemistry> A common misuse of the term receptor. Con A binds to the mannose residues of many different glycoproteins and glycolipids and the binding is therefore not to a specific site. It could be argued that the receptor is the Con A and cells have Con A ligands on their surfaces: certainly this would be less confusing. (05 Jan 1998) |
| multiple cloning site | Region of a phage or plasmid vector that has been engineered to contain a series of restriction sites that are usually unique within the entire vector. This makes it particularly easy to insert or excise (subclone) DNA fragments. (18 Nov 1997) |
| mutagenesis, site-directed | Mutagenesis where the mutation is caused by in vitro induction directed at a specific site in a DNA molecule. The most common method involves use of a chemically synthesised oligonucleotide mutant which can hybridise with the DNA target molecule. The resulting mismatch-carrying DNA duplex may then be transfected into a bacterial cell line and the mutant strands recovered. (12 Dec 1998) |