BIO 325 Lecture Notes - Meiosis, Klinefelter Syndrome, Germ Cell
29 Sep 2013
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Document Summary
Sex determination is done by looking at the sex chromosomes --- but the sex determining genes aren"t always present on the sex chromosomes. -- in mice, some sex determining genes are present on the autosomes. Primary sexual differentiation - involves only the gonads where gametes are produced. Secondary sexual differentiation - the overall appearance of the organism. There are situations where primary and secondary sex are different! Unisexual (dioecious or gonochoric) - individuals that contain only male or female reproductive organs. Bisexual (monoecious or hermaphroditic) - individuals that contain both male and female reproductive organs (can produce both male and female gametes) Chlamydomonas (algae) -- produces asexually and spends most of their life cycle in haploid phase. Unfavorable nutrient conditions --> certain daughter cells function as gametes: the two gametes fuse together during mating that aren"t usually morphologically distinguishable. Two mating types: mt- and mt: subtle chemical differences; behave differently, mt- cells can mate only with mt+ cells.
