| ligand-gated channel | A class of ion channel's whose ionic permeability is regulated by cell membrane receptors that respond to specific extracellular chemical signals. (05 Mar 2000) |
|---|---|
| ligand gated ion channel | A transmembrane ion channel whose permeability is increased by the binding of a specific ligand, typically a neurotransmitter at a chemical synapse. The permeability change is often drastic, such channels let through effectively no ions when shut, but allow passage at up to 10exp7 ions sexp 1 when a ligand is bound. Recently, the receptors for both acetylcholine and GABA have been found to share considerable sequence homology, implying that there may be a family of structurally related ligand gated ion channels. (18 Nov 1997) |
| polymorphism, single-stranded conformational | Variation occurring within a species in the conformation of denatured DNA fragments. These single-stranded DNA fragments are allowed to partially renature in a way that prevents the formation of double-stranded DNA. The fragments are run on polyacrylamide gels under various conditions to detect subtle changes in migration due to altered secondary structure. The resulting bands will align themselves if the fragments are the same, but will misalign if any point mutations are present. Sscps have been used in detecting mutations in various genes, such as oncogenes, tumour suppressor genes, and genes responsible for genetic diseases. (12 Dec 1998) |
| single | 1. One only, as distinguished from more than one; consisting of one alone; individual; separate; as, a single star. "No single man is born with a right of controlling the opinions of all the rest." (Pope) 2. Alone; having no companion. "Who single hast maintained, Against revolted multitudes, the cause Of truth." (Milton) 3. Hence, unmarried; as, a single man or woman. "Grows, lives, and dies in single blessedness." (Shak) "Single chose to live, and shunned to wed." (Dryden) 4. Not doubled, twisted together, or combined with others; as, a single thread; a single strand of a rope. 5. Performed by one person, or one on each side; as, a single combat. "These shifts refuted, answer thy appellant, . . . Who now defles thee thrice ti single fight." (Milton) 6. Uncompounded; pure; unmixed. "Simple ideas are opposed to complex, and single to compound." (I. Watts) 7. Not deceitful or artful; honest; sincere. "I speak it with a single heart." (Shak) 8. Simple; not wise; weak; silly. "He utters such single matter in so infantly a voice." (Beau & Fl) Single ale, beer, or drink, small ale, etc, as contrasted with double ale, etc, which is stronger. Single bill, a single rope running through a fixed block. Origin: L. Singulus, a dim. From the root in simplex simple; cf. OE. & OF. Sengle, fr. L. Singulus. See Simple, and cf. Singular. 1. To select, as an individual person or thing, from among a number; to choose out from others; to separate. "Dogs who hereby can single out their master in the dark." (Bacon) "His blood! she faintly screamed her mind Still singling one from all mankind." (More) 2. To sequester; to withdraw; to retire. "An agent singling itself from consorts." (Hooker) 3. To take alone, or one by one. "Men . . . Commendable when they are singled." (Hooker) Origin: Singled; Singling. Source: Websters Dictionary (01 Mar 1998) |
| single ascertainment | Method of ascertainment of locating affected individuals by hospital or clinic admission or another way in which probability of encountering the same family twice approaches zero; thus, the probability that a family will be ascertained is proportional to the number of affected members. (05 Mar 2000) |
| single-blind method | A method in which either the observer(s) or the subject(s) is kept ignorant of the group to which the subjects are assigned. (12 Dec 1998) |
| single bond | A covalent bond resulting from the sharing of one pair of electrons; e.g., H3C-CH3 (ethane). (05 Mar 2000) |
| single cell protein | <protein> Protein produced by single cells in culture, especially Candida species, that could be of possible commercial importance in providing food sources from biotechnological processes. (10 Oct 1997) |
| single-foot | An irregular gait of a horse; called also single-footed pace. See Single, "Single-foot is an irregular pace, rather rare, distinguished by the posterior extremities moving in the order of a fast walk, and the anterior extremities in that of a slow trot." (Stillman (The Horse in Motion)) Source: Websters Dictionary (01 Mar 1998) |
| single-gene diseases | Hereditary disorders caused by a change (mutation) in a single gene. There are thousands of single-gene diseases including achondroplastic dwarfism, huntington disease, cystic fibrosis, sickle cell disease, duchenne muscular dystrophy, and haemophilia. Single-gene diseases typically describe classic simple mendelian patterns of inheritance (as autosomal dominant, autosomal recessive, and x-linked traits) by comparison with polygenic diseases. (12 Dec 1998) |
| single gene disorder | Hereditary disorder caused by a mutant allele of a single gene (for example, Duchenne muscular dystrophy, retinoblastoma, sickle cell disease). Compare: polygenic disorders. (09 Oct 1997) |
| single-hearted | Having an honest heart; free from duplicity. Sin"gle-heart"edly. Source: Websters Dictionary (01 Mar 1998) |
| single immunodiffusion | See: gel diffusion precipitin tests in one dimension, gel diffusion precipitin tests in two dimensions. (05 Mar 2000) |
| single lucent skull lesion | <radiology> Mnemonic: HELP ME, haemangioma, epidermoid / dermoid, leptomeningeal cyst, lambdoid suture defect, Paget's (osteoporosis circumscripta), post-surgical, metastasis (solitary), eosinophilic granuloma, encephalocele (12 Dec 1998) |
| single-minded | Having a single purpose; hence, artless; guileless; single-hearted. Source: Websters Dictionary (01 Mar 1998) |