Locus (genetics)

<p>In <a href="/facts/Genetics/bu8wne0A">genetics</a>, a locus (pl.: loci) is a specific, fixed position on a <a href="/facts/Chromosome/FRGf11FC">chromosome</a> where a particular <a href="/facts/Gene/e1swwPY6">gene</a> or <a href="/facts/Genetic_marker/pRshdIBz">genetic marker</a> is located. Each chromosome carries many genes, with each gene occupying a different position or locus; in humans, the total number of <a href="/facts/Human_genome/VTV85pbn">protein-coding genes</a> in a complete <a href="/facts/Haploid/U8zl4AQe">haploid</a> set of 23 chromosomes is estimated at 19,000–20,000.
</p><p>Genes may possess multiple variants known as <a href="/facts/Allele/8FxCS9KA">alleles</a>, and an allele may also be said to reside at a particular locus. <a href="/facts/Diploid/U8zl4AQe">Diploid</a> and <a href="/facts/Polyploid/L7xyKHdK">polyploid</a> cells whose chromosomes have the same allele at a given locus are called <a href="/facts/Homozygote/XzEJ5gPp">homozygous</a> with respect to that locus, while those that have different alleles at a given locus are called <a href="/facts/Heterozygote/XzEJ5gPp">heterozygous</a>. The ordered list of loci known for a particular <a href="/facts/Genome/31Sm08JT">genome</a> is called a <a href="/facts/Gene_map/hIRffUwq">gene map</a>. <a href="/facts/Gene_mapping/QnC0Vvjx">Gene mapping</a> is the process of determining the specific locus or loci responsible for producing a particular <a href="/facts/Phenotype/vxWXKGLj">phenotype</a> or <a href="/facts/Biological_trait/seYSUTul">biological trait</a>. <a href="/facts/Association_mapping/Jn1IAdHo">Association mapping</a>, also known as "linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of historic linkage disequilibrium to link phenotypes (observable characteristics) to genotypes (the genetic constitution of organisms), uncovering genetic associations.
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Locus (genetics) open-in-new

Locus (genetics)