| 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) |
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| chi | 1. The 22nd letter of the Greek alphabet, χ. 2. In chemistry, denotes the 22nd in a series. 3. Symbol for the dihedral angle between the alpha-carbon and the side-chains of amino acids in peptides and proteins. (05 Mar 2000) |
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| chi sequence | <molecular biology> A specific sequence of nucleotides on a site on the genome of the bacteria Escherichia coli which strongly encourages recombination and crossing over to occur at that site. (05 Jan 1998) |
| chi-sequences | A specific DNA sequence in bacterial genomes that allows for extensive genetic recombination. (05 Mar 2000) |
| chi-square | A statistical technique whereby variables are categorised to determine whether a distribution of scores is due to chance or experimental factors. (05 Mar 2000) |
| chi squared | <statistics> Common statistical test to determine whether the observed values of a variable are significantly different from those expected on the basis of a null hypothesis. (18 Nov 1997) |
| chi-square distribution | A distribution in which a variable is distributed like the sum of the the squares of any given independent random variable, each of which has a normal distribution with mean of zero and variance of one. The chi-square test is a statistical test based on comparison of a test statistic to a chi-square distribution. The oldest of these tests are used to detect whether two or more population distributions differ from one another. (12 Dec 1998) |
| chi-square test | A statistical method of assessing the significance of a difference, as when the data from two or more samples is represented by a discrete number such as the numbers of females and males attending each of two colleges. Synonym: x2 test. (05 Mar 2000) |
| chi structure | <molecular biology> The name for the X-shaped structure which forms during the recombination process between two plasmids, or circular pieces, of DNA. The Greek letter chi resembles this structure. (05 Jan 1998) |
| acceptor site | The ribosomal binding site for the aminoacyl-tRNA during protein synthesis. (05 Mar 2000) |
| acceptor splicing site | Boundary between the right end of an intron and the left end of the adjacent exon. Synonym: acceptor splicing site. (05 Mar 2000) |
| active site | <chemistry> A specific region of an enzyme where a substrate binds and catalysis takes place (binding site). (06 May 1997) |
| allosteric site | A specific site on a multi-subunit enzyme or other protein that is not the substrate binding site, but that when reversibly bound by an effector, induces a conformational change in the protein, altering its catalytic or binding properties. (12 Dec 1998) |
| amidation site | <molecular biology> A C terminus consensus sequence, required for C terminus amidation of peptides. Consensus is glycine, followed by 2 basic amino acids (arg or lys). (18 Nov 1997) |
| antibody combining site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |
| antigen-binding site | <immunology> In immune network theory, an idiotope, an antigenic site of an antibody that is responsible for that antibody binding to an antigenic determinant (epitope). Also used of the site on a ligand molecule to which a cell surface receptor binds. (18 Nov 1997) |