Tetrad: In the context of yeastplugin-autotooltip__default plugin-autotooltip_bigYeast: in this book, refers to Saccharomyces cerevisiae, a single-celled eukaryotic microbe used as a model genetic organism. See Chapter 02 genetics, a tetrad refers to the four ascosporesplugin-autotooltip__default plugin-autotooltip_bigSpore: in fungi (including yeast), ascospores (spores) are the equivalent of the four daughter cells of meiosis. from a single ascus, which represents the four products of a single meiotic event. In the context of meiosisplugin-autotooltip__default plugin-autotooltip_bigMeiosis: a process involving two sequential cell divisions that usually produces four gametes (reproductive cells such as sperm or eggs). in general, a tetrad refers to the four chromatidsplugin-autotooltip__default plugin-autotooltip_bigChromatid: a chromosome-like structure, two of which are formed after replication of a chromosome in both mitosis and meiosis. from a set of replicated homologous chromosomesplugin-autotooltip__default plugin-autotooltip_bigHomologous chromosomes: highly similar but non-identical chromosomes that are the same size and contain the same genes. lined up at metaphase I.