Hypermedia Glossary Of Genetic Terms
|Genetic distance||A way of measuring the amount of evolutionary divergence in two separated populations of a species by counting the number of allelic substitutions per locus that have cropped up in each population.|
|Population||A group of organisms of the same species relatively isolated from other groups of the same species. See deme.|
|Species||A group of organisms belong to the same biological species, if they are capable of interbreeding to produce fertile offspring. However the biological test of a species is not always available, and so there is also a morphological species concept based on anatomical similarities.|
|Allele||The term coined by Bateson and Saunders (1902) for characters which are alternative to one another in Mendelian inheritance (Gk. Allelon, one another; morphe, form).
Now the term allele is used for two or more alternative forms of a gene resulting in different gene products and thus different phenotypes. In a haploid set of chromosomes there is only one allele at its specific locus. Diploid organisms have 2 alleles at a given locus, i.e. a normal and a mutant allele. A single allele for each gene locus is inherited separately from each parent (e.g., at a locus for eye colour the allele might result in blue or brown eyes). An organism is homozygous for a gene if the alleles are identical, and heterozygous if they are different.
|Locus||The position of a gene on a chromosome or other chromosome markers; also, the DNA at that position. The use of the term locus is sometimes restricted to main regions of DNA that are expressed. Plural: loci. See gene expression.|
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