GENE20001 Lecture Notes - Lecture 21: Shmoo, Fine Structure, Genetic Linkage
Document Summary
Alpha mating type and a mating type recognise each other as they secrete pheromones. They form a shmoo that allows them to fuse. Nuclei fuse (karyogamy) producing a diploid cell which undergoes meiosis to produce an ascus with 4 meiotic product that is random. Mutations used in analysis of haploid eukaryotes include auxotrophic, utilisation, morphological and developmental phenotypes. Linkage is determined by constructing maps where the distance between any two markers is. There are no requirements for a test cross as the progeny are haploid and so the phenotype is the genotype. In all other respects the data can be handled as for diploids. In tetrad analysis each possibility is one bag of meiotic products from a single meiosis event. These are unordered tetrads so the presented order is random. Asci which contain two genotypes are called ditypes (the first two possibilities in the diagram above) Asci which contain four genotypes are called tetratypes.
