| structural isomerism | Isomerism involving the same atoms in different arrangements; e.g., butyric acids, leucine and isoleucine, glucose and fructose. (05 Mar 2000) |
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| structural isomers | <chemistry> Are organic compounds that have the same som formula, meaning the same number of carbons, hydrogens or other type ot atoms. They differ from each other in the way the atoms are connected. Examples are n-butane and 2-methylpropane or ethanol and dimethylether. (09 Jan 1998) |
| geometric isomer | <chemistry> Geometric or also called cis-trans isomers are stereoisomers in molecules with restricted rotation about a bond. Cycloalkanes and alkenes form cis-trans isomers due to the restriction of rotation about the double bond or due to the restriction in a ring. In order for an alkene to freely rotate, the pi bond must be broken. This process has a high activation energy and does not occur at room temperature. Cis isomers have the two substituents on each of the carbons of the double bond on the same side, whereas in the trans isomer they are on opposite sides. The expression cis and trans only applies to alkenes or cycloalkanes if one of the substituents on each of the carbons are the same. If there are three or four different substituents, E,Z or R,S nomenclature must be used. (09 Jan 1998) |
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| chain isomer | <chemistry> One of two or more compounds having the same chemical composition but differing in the arrangement of the atoms (usually carbon atoms) forming the backbone of the structure of the compounds. (21 Mar 1998) |
| dextrorotatory isomer | A stereoisomer that does a clockwise rotation of plane-polarized light. (09 Oct 1997) |
| isomer | 1. <chemistry> One of two or more molecules that have the same chemical formula but have a different stereochemical arrangement of their atoms. 2. <radiobiology> Nuclides having the same number of neutrons and protons but capable of existing, for a measurable time, in different quantum states with different energies and radioactive properties. Commonly, the isomer of higher energy decays to one of lower energy by the process of isomeric transition. (13 Nov 1997) |
| levorotatory isomer | A stereoisomer that rotates the plane of polarized light counterclockwise. (09 Oct 1997) |
| genes, structural | Genes that code for proteins required for the enzymatic and structural functions of cells. They include developmental and differentiated genes. (12 Dec 1998) |
| genes, structural, bacterial | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of bacterial cells. (12 Dec 1998) |
| genes, structural, fungal | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of fungal cells. (12 Dec 1998) |
| genes, structural, helminth | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of helminthic cells. (12 Dec 1998) |
| genes, structural, insect | DNA sequences that code for RNA and for proteins required for the enzymatic and structural function of insect cells. (12 Dec 1998) |
| genes, structural, neoplasm | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of neoplastic cells. (12 Dec 1998) |
| genes, structural, plant | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of plant cells. (12 Dec 1998) |
| genes, structural, protozoan | DNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of protozoan cells. (12 Dec 1998) |
| genes, structural, viral | DNA or RNA sequences that code for RNA and for the proteins required for the enzymatic and structural function of viral cells. (12 Dec 1998) |
| viral structural proteins | Viral proteins that do not regulate transcription. They are coded by viral structural genes and include nucleocapsid core proteins (gag proteins), enzymes (pol proteins), and membrane components (env proteins). Transcription of viral structural genes is regulated by viral regulatory proteins. (12 Dec 1998) |