7.013 Genetic Nomenclature David Gifford and Megan Rokop Version 1.4 / February 28, 2007 Goals • Be simple and consistent • Not encode inappropriate information • Encompass Mendel’s plant genetics • Encompass gene linkage • Encompass sex-linked traits • Minimize confusing differences with Purvis et. al. Principles • For each area of study, we will endeavor to provide a table of the form: Character Phenotype Dominance Genotypes “pea shape” smooth smooth > s S, S s, S S wrinkled wrinkled s s Allele Abbreviation Full Name of Gene / Allele S SBE1 s Sbe1-1 Nomenclature rules • Character: Sentence • Phenotype: single word, begins with lower case letter, at least two characters, can be hyphenated. + and – modifiers can be added to further describe a phenotype (e.g. Arg- cells can not grown on medium without Arg). + and – modifiers are not used on genes or alleles. • Gene: single word, begins with upper case letter, at least two characters. An UPPER CASE gene name denotes the wild type form of a gene, or in the case of human, the sequence that is in the human genome database. • Allele: Gene suffixed with dash and a numeral, indicating the allele. • Allele Shorthand: single character • Dominance: binary relationship between related phenotypes of a character. Genotypes • Unless otherwise specified by the genotype, all of the genes in an organism are assumed to be wild type • If there is a non wild type allele, then all of the alleles of that gene are specified. The following two notations are identical: S s SBE1 Sbe1-1 • Autosomal linked genes are written in their chromosomal order, alleles on homologous chromosomes are separated by a “/”, and the entire linkage group is optionally surrounded by parenthesis. B V / b v (B V / b v)• Sex linked genes are written as superscripts on their respective chromosome in chromosomal order. Parenthesis around the linked genes can be added for clarity. Xy wXY W Xy wY X(y w)X(Y W) X(y w)Y Note that when genes do not appear on a specific sex chromosome they are omitted. • Linked alleles can also drawn on a genetic map: B 17 cm
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