内蒙古大学遗传学双语教学课件.pptVIP

CHAPTER 5 5.1 X and Y Chromosomes （2）Clarance McLung （3）Edmund B. Wilson ② Insect Lygaeus turicus（属半翅目）： ③ Protenor mode——XX/XO mode ④ Lygaeus mode——XX/XY mode （3）ZZ/ZW mode 5.2 Human Sex Determination （3） Hin Tjio and Albert Levan 2. Human Chromosome Composition Normal male Normal female 3. Role of XY in Sex Determination ① Klinefelter syndrome Karyotype of Klinefelter syndrome ② Turner syndrome Karyotype of Turner syndrome （3）Role of XY in Sex determination 4. Y chromosome and Male Development Some portions of MSY share homology with X. （2）Genes on Y Chromosome SRY binds to DNA and distorts its shape Y determine testes Gonad development Examples: ② Other genes on MSY 5. Effect of X on Male Determination 5.3 Human Sex Ratio 1. Primary Sex Ratio 2. Secondary Sex Ratio Census（人口普查）data 5.4 Dosage Compensation 1. Barr Bodies——sex chromatin body Barr body in buccal mucosa（人口腔粘膜） 2. Dosage Compensation （剂量补偿） ——X inactivation 3. Questions about X Inactivation 4. The Lyon Hypothesis ① Calico cat（玳瑁猫） Random inactivation form mosaic pattern ② G6PD expression ③ Anhidrotic ectodermal dysplasia（缺汗表皮发育异常，汗腺缺乏） ④ Red-green color blindness ⑤ Microscopy 5. The Mechanism of Inactivation （4）Remaining questions （5）Genes escape from inactivation: 5.5 Sex Determination in Drosophila（果蝇） 3. Bridges’s Hybridization Experiment （1）Hybridization Results （2）Bridges’s conclusion 5.6 Sex Determination in Reptiles（爬行类） 2. By Temperature （2）Case I （3）Case II （4）Case III （5）Characteristics of TSD Should be 1:1 Equal number of X- and Y-bearing sperm. 22 X 44 XX 44 XY 22 X 22 X The proportion of males to females conceived（设想） in a population. Expected male number Primary sex ratio Expected female number = = 1 Males born Females born Secondary sex ratio Proportion of each sex is born. 1 = 1969: African-American Caucasian：1.06 African-American：1.025 Korea：1.15 Many more males than females are born in population. Possible explanation: Y-bearing sperm is smaller and more motile than X