Locus
The place, in Latin.. In genetics, a locus is the place a gene occupies on a chromosome. One locus, two loci.
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1. A place; usually, a specific site. 2. The position that a gene occupies on a chromosome. 3. The position of a point, as defined by the coordinates on a graph. [L.]
- l. caeruleus [TA] a shallow depression, of a blue color in the fresh brain, lying laterally in the most rostral portion of the rhomboidal fossa near the cerebral aqueduct; it lies near the lateral wall of the fourth ventricle and consists of about 20,000 melanin-pigmented neuronal cell bodies whose norepinephrine-containing axons have a remarkably wide distribution in the cerebellum as well as in the hypothalamus and cerebral cortex. SYN: l. cinereus, l. ferrugineus, substantia ferruginea.
- l. cinereus SYN: l. caeruleus.
- cis-acting l. a section of DNA that affects the activity of DNA sequences on that same molecule of DNA.
- complex l. a set of closely linked genetic loci with a common function, as in the major histocompatibility complex l..
- l. of control a theoretical construct designed to assess a person's perceived control over his/her own behavior; classified as internal if the person feels in control of events, external if others are perceived to have that control.
- l. ferrugineus SYN: l. caeruleus.
- genetic l. the set of homologous parts of a pair of chromosomes that may be occupied by allelic genes. The l. thus comprises a pair of locations (except in the X chromosome in males). The concept of a l. is somewhat idealized, not taking into account accidents that may occur in meiosis such as duplication of loci as a result of unequal crossing-over, translocations, inversions, etc.
- marker l. a l. on a chromosome or in a stretch of DNA that can be identified ( e.g., a restriction fragment length polymorphism) and can serve in linkage analysis and in the isolation of a disease gene. SEE ALSO: linkage marker.
- l. niger SYN: substantia nigra.
- l. perforatus anticus SYN: anterior perforated substance.
- l. perforatus posticus SYN: posterior perforated substance.
- sex-linked l. any l. that in normal karyotypes is borne on a heterosome; commonly but incorrectly applied to an X-linked l..
- X-linked l. any l. that in normal karyotypes is borne on the X chromosome.
- Y-linked l. any (haploid) l. that in normal karyotypes is borne on the Y chromosome. The known content is so far small.

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lo·cus 'lō-kəs n, pl lo·ci 'lō-.sī, -.kīalso -.kē
1) a place or site of an event, activity, or thing <the integrity of the tissues determines the extent and \locus of the damage (Sylvia E. Hines)>
2) the position in a chromosome of a particular gene or allele

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n.
1. (in anatomy) a region or site. The locus caeruleus is a small pigmented region in the floor of the fourth ventricle of the brain.
2. (in genetics) the region of a chromosome occupied by a particular gene.

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lo·cus (loґkəs) gen. and pl. loґci [L. “a place”] 1. a place or site, as in the body. 2. in genetics, the position of a gene on a chromosome, different forms of genes (alleles) being found at the same position on homologous chromosomes. The standard method of designating a locus consists of the chromosome number; p (short arm) or q (long arm); region and band number written without separation (11, 12, 13, etc.), moving outward from the centromere; sub-band and sub-sub-band, again written without separation. The centromere is designated by "cen" and the telomere or terminal by "ter."

Medical dictionary. 2011.

Look at other dictionaries:

  • locus — [ lɔkys ] n. m. • 1865; mot lat. « lieu » ♦ Biol. Localisation précise d un gène particulier sur un chromosome. Locus complexe. Locus létal. Des locus ou des loci [ lɔki; lɔsi ]. ● locus nom masculin (latin locus, lieu) Emplacement précis d un… …   Encyclopédie Universelle

  • locus — lo·cus / lō kəs/ n: the place connected with a particular event having legal significance Merriam Webster’s Dictionary of Law. Merriam Webster. 1996. locus …   Law dictionary

  • Locus — Lo cus, n.; pl. {Loci}, & {Loca}. [L., place. Cf. {Allow}, {Couch}, {Lieu}, {Local}.] 1. A place; a locality. [1913 Webster] 2. (Math.) The line traced by a point which varies its position according to some determinate law; the surface described… …   The Collaborative International Dictionary of English

  • LOCUS — unde dictus sit, exponit hisce Iul. Caes. Scalig. poët. l. 3. c. 89. Locum παρὰ τὸν λόγον dicimus: quia proportio est inter locum et locatum. Λόγος insidiae dicuntur, quia veteres Graeci locum priscâ et abolitâ voce sic appellabant: etiam inter… …   Hofmann J. Lexicon universale

  • locus — (izg. lȍkus) m DEFINICIJA mjesto SINTAGMA locus communis (izg. locus komúnis) »opće mjesto«, izraz kojim se označuje neki poznat, uobičajen, banalan misaoni pojam; locus delicti (izg. locus delìkti) mjesto počinjena zločina ETIMOLOGIJA lat …   Hrvatski jezični portal

  • locus — anat. Voz latina que significa lugar. Medical Dictionary. 2011. locus Lugar o posición determ …   Diccionario médico

  • locus — LÓCUS pl. ci/ s. m. poziţie determinată ocupată de o genă sau de alelele ei în structura cromozomului. (< lat. locus) Trimis de raduborza, 15.09.2007. Sursa: MDN …   Dicționar Român

  • locus — (pl. loci), 1715, locality, from L. locus a place, spot, position, from O.Latin stlocus, lit. where something is placed, from PIE root *st(h)el to cause to stand, to place. Used by Latin writers for Gk. topos. Mathematical sense by 1750 …   Etymology dictionary

  • locus — s. m. [Genética] Ver lócus. • Plural: loci.   ‣ Etimologia: palavra latina …   Dicionário da Língua Portuguesa

  • lócus — s. m. 2 núm. [Genética] Local específico de um cromossomo onde está situado um gene.   ‣ Etimologia: latim locus, i, lugar, sítio, localidade …   Dicionário da Língua Portuguesa

  • locus — locus. См. локус. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

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