| Arrhenius plot | A plot of the logarithm of reaction rate against the reciprocal of absolute temperature. For a single stage reaction this gives a straight line from which the activation energy and the frequency factor can be determined. Often applied to data from complex biological systems when the form observed is frequently a series of linear portions with sudden changes of slope. Great caution must be observed in interpreting such slopes in terms of activation energies for single processes. (18 Nov 1997) |
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| black box | (Jargon) descriptive of a method of reasoning or studying a problem, in which the methods and procedures, as such, are not described, explained, or perhaps even understood: conclusions relate solely to the empirical relationships observed, in some contexts, the term can mean a piece of apparatus or an experimental animal in which the pharmacologic or toxicologic pathway has not yet been worked out. CAAT box, a sequence of nucleotides found in a conserved region of DNA located "upstream" (5' direction) of the start points of eukaryotic transcription units; specific transcription factors appear to associate with it; found in many promoters at -75 bp with the consensus sequence: GG(T/C)CAATCT. Fracture box, an obsolete means of supporting a fractured leg, consisting of a container with only bottom and sides. (05 Mar 2000) |
| box | <molecular biology> Casual term for a DNA sequence that is a characteristic feature of regions that bind regulatory proteins for example homeobox, TATA box and CAAT box. (18 Nov 1997) |
| box-like heart | <radiology> Ebstein's anomaly, massive cardiomegaly, primarily RA enlargement (12 Dec 1998) |
| CAAT box | <molecular biology> Nucleotide sequence in many eukaryotic promoters usually about 75bp upstream of the start of transcription. Binds NF1. (18 Nov 1997) |
| paired box domain | <molecular biology> Conserved domain of 128 amino acids, found in several developmentally regulated proteins in Drosophila (for example paired, gooseberry, Pox), mouse and human (for example Pax, HuP1, HuP48). (18 Nov 1997) |
| Ramachandran plot | A graphical representation in which the dihedral angle of rotation about the alpha-carbon to carbonyl-carbon bond in polypeptides is plotted against the dihedral angle of rotation about the alpha-carbon to nitrogen bond. Synonym: conformational map. (05 Mar 2000) |
| GC box | <molecular biology> A binding site within the promoter region of cells from mammals which has the general nucleotide sequence of GGGCGG and where transcription factors will bind. (20 Mar 1998) |
| CCAAT box | <molecular biology> Consensus sequence for RNA polymerase, found at about 80 bases relative to the transcription start site. Less well conserved than the TATA box. (18 Nov 1997) |
| Woolf-Lineweaver-Burk plot | <statistics> A graph made to analyse how fast an enzyme can convert its substrate into its product, depending on how much substrate is present (its concentration) and to determine its maximum speed (after which the enzyme does not get any faster no matter how high the concentration of substrate gets), called Vmax. It is a plot of 1/v versus 1/[S], where v=rate of product formation and [S]=the concentration of the substrate. Synonym: Lineweaver-Burk plot, Woolf-Lineweaver-Burk plot. (05 Mar 2000) |
| plot | 1. A small extent of ground; a plat; as, a garden plot. 2. A plantation laid out. 3. A plan or draught of a field, farm, estate, etc, drawn to a scale. Origin: AS. Plot; cf. Goth. Plats a patch. Cf. Plat a piece of ground. 1. Any scheme, stratagem, secret design, or plan, of a complicated nature, adapted to the accomplishment of some purpose, usually a treacherous and mischievous one; a conspiracy; an intrigue; as, the Rye-house Plot. "I have overheard a plot of death." (Shak) "O, think what anxious moments pass between The birth of plots and their last fatal periods!" (Addison) 2. A share in such a plot or scheme; a participation in any stratagem or conspiracy. "And when Christ saith. Who marries the divorced commits adultery, it is to be understood, if he had any plot in the divorce." (Milton) 3. Contrivance; deep reach thought; ability to plot or intrigue. "A man of much plot." 4. A plan; a purpose. "No other plot in their religion but serve Got and save their souls." 5. In fiction, the story of a play, novel, romance, or poem, comprising a complication of incidents which are gradually unfolded, sometimes by unexpected means. "If the plot or intrigue must be natural, and such as springs from the subject, then the winding up of the plot must be a probable consequence of all that went before." (Pope) Synonym: Intrigue, stratagem, conspiracy, cabal, combination, contrivance. Origin: Abbrev. From complot. Source: Websters Dictionary (01 Mar 1998) |
| control plot | A plot in which no vegetation will be cut and natural succession will occur. A control plot serves as a baseline to compare other treatments (Early, Mid and Late Seral). (05 Dec 1998) |
| Hanes plot | A graphical representation of enzyme kinetic data in which the substrate concentration divided by the velocity (i.e., the [S]/v ratio) is plotted on the vertical axis as a function of [S]. Sometimes referred to as the Hanes-Wilkinson plot. (05 Mar 2000) |
| Pribnow box | <molecular biology> A region of DNA to which RNA polymerase binds before initiating the transcription of DNA into RNA. The nucleotide at which transcription starts is designated +1 and nucleotides are numbered from this with negative numbers indicating upstream nucleotides and positive downstream nucleotides. most bacterial promoters contain two consensus sequences that seem to be essential for the binding of the polymerase. The first, the Pribnow box, is at about 10 and has the consensus sequence 5' TATAAT 3'. The second, the 35 sequence, is centred about 35 and has the consensus sequence 5' TTGACA 3'. most factors that regulate gene transcription do so by binding at or near the promoter and affecting the initiation of transcription. Much less is known about eukaryote promoters, each of the three RNA polymerases has a different promoter. RNA polymerase I recognises a single promoter for the precursor of rRNA. RNA polymerase II, that transcribes all genes coding for polypeptides, recognises many thousands of promoters. most have the Goldberg Hogness or TATA box that is centred around position 25 and has the consensus sequence 5' TATAAAA 3'. Several promoters have a CAAT box around 90 with the consensus sequence 5' GGCCAATCT 3'. There is increasing evidence that all promoters for housekeeping genes contain multiple copies of a GC rich element that includes the sequence 5' GGGCGG 3'. Transcription by polymerase II is also affected by more distant elements known as enhancers. RNA polymerase III synthesises 5s ribosomal RNA, all tRNAs and a number of small RNAs. The promoter for RNA polymerase III is located within the gene either as a single sequence, as in the 5s RNA gene or as two blocks, as in all tRNA genes. (13 Nov 1997) |
| Scatchard plot | A method for analysing data for freely reversible ligand/receptor binding interactions. The graphical plot is: Bound ligand/Free ligand) against (Bound ligand), the slope gives the negative reciprocal of the binding affinity, the intercept on the x axis the number of receptors (Bound/Free becomes zero at infinite ligand concentration). The Scatchard plot is preferable to the Eadie Hoffstee plot for binding data because it is more dependent upon the values at high ligand concentration which will be the most reliable values. A nonlinear Scatchard plot is often taken to indicate heterogeneity of receptors, although this is not the only explanation possible. (18 Nov 1997) |