BI226 Study Guide - Triple X Syndrome, Klinefelter Syndrome, 49,Xxxxx
Document Summary
Chapter 5 sex determination and sex chromosomes: heteromorphic chromosomes. X and y: unisexual, dioecious and gonochoric. Contain only male or female reproductive organs: bisexual, monoecious and hermaphroditic. Contain both male and female reproductive organs. Modes of sex determination: protenor mode (xx & xo) Lygaeus mode (xx & xy) or (zz & zw) In both cases one sex produces two types of gametes (heterogametic sex) while the other produces only one type of gamete (homogametic sex). Tall, long arms & legs, large hands & feet. Slight decrease in intelligence (below normal range: result of nondisjunction event in parent. Female external genitalia and internal ducts: 1 in 10,000 female births, ovaries not fully developed, result of nondisjunction event in parent. Short stature, skin flaps on back of neck and underdeveloped breasts. 47,xxx syndrome: occurs in about 1 of every 1,200 female births, observe variable expression:
