BIOL239 Lecture Notes - Lecture 5: Meiosis, Mitosis, Y Chromosome
26 Jan 2018
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Document Summary
Earliest indications: studies show that semen contains spermatozoa (indicated specialized cells contribute to this trait f sex- there must be something in these cells) reproduction in frogs and sea urchin showing union of male and female gametes. Observation of threadlike structures in nuclei of salamander cells. Dye used for differential staining of cytoplasm, nucleus, and nuclear clear structures linking chromosomes to mendelian principles of segregation and independent assortment: proposed that each egg or sperm contains only one of each chromosome pair lead to Chromosome theory of inheritance: states that heredity info is on genes and genes are located on chromosomes, that egg and sperm contribute equally to the genetic endowment of offspring through their nuclei. The x and y determined sex in grasshoppers. Confirmed separate sex chromosome in other species too. Different from mammals, birds, butterflies, and some reptiles: male-zz, female-zw. Sex is not determined by x and y chromosome in all species.
