Tetrad (genetics)

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The tetrad is the four spores of a yeast, that separate after mating. If the two parents have a mutation in two different genes, the tetrad can segregate as the parental ditype, the non-parental ditype or as the tetratype.

Contents 1 Parental ditype 2 Non-parental ditype 3 Tetratype 4 Linkage analysis

[edit] Parental ditype

A tetrad type containing two different genotypes, both of which are parental. A spore arrangement in Ascomycetes that contains only the two non-recombinant-type ascospores.

[edit] Non-parental ditype

A spore arrangement in Ascomycetes that contains only the two recombinant-type ascospores (assuming two segregating loci). A tetrad type containing two different genotypes, both of which are recombinant.

[edit] Tetratype

A Tetratype is a tetrad containing four different genotypes, two parental and two recombinant. A spore arrangement in Ascomycetes that consists of two parental and two recombinant spores indicating a single crossover between two linked loci.

[edit] Linkage analysis

The ratio between the different types arising after the sporulation is a measure of the linkage between the two genes.