GEN-3000 Lecture Notes - Lecture 5: Haplodiploidy, Sequential Hermaphroditism, Zw Sex-Determination System
20 Feb 2017
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Sexual reproduction formation of offspring that are genetically distinct from parents. Sex (noun) defined by phenotype of individual (not genotype) Monoecious - one house - has both female and male reproductive structures. Dioecious - two house - individual has either female or male reproductive structures. Chromosomal sex-determining system and chromosomes are substrate for gene segregation. Remember : chromosome theory of inheritance - genes are located on chromosomes. Henking (1891) - male insects had a strange body in nuclei x body. Female grasshopper cells had 1 more chromosome than males. Stevens and wilson (1905) - female grasshopper have two x chromosomes. Also, x in male cells with smaller chromosome (called y ) X and y separated into different sperm cells, while egg cells all. Remember : sex is associated with the inheritance of a particular chromosome (sex chromosomes) genes are therefore on chromosomes. Xx-xy - some plants, insects, reptiles and all mammals.
