1、遗传的物质和细胞学基础,Chapter 1The material and Cytological Foundation of Heredity,Main contents,1 Spermatogenesis and Oogenesis（精子和卵子的发生） 2 meiosis（减数分裂）,教学目的要求,The development of Gametes（熟悉配子发生过程）Characteristics and Significance of meiosis（熟悉减数分裂的主要特点及意义）,1 Spermatogenesis and Oogenesis （精子和卵子的发生）,1.Spermat
2、ogenesis（精子的发生）2.Oogenesis（卵子的发生）3.Differences Between Sperm and Egg （精子和卵子的异同）,46XY,46XY,1.Spermatogenesis,精原细胞(2n),初级精母细胞(2n),次级精母细胞(n),精细胞(n),精子(n),46XX,46XX,卵原细胞(2n),初级卵母细胞(2n),次级卵母细胞(n),卵细胞(n),第一极体(n),第二极体(n),2.Oogenesis,四个月至偶线期,七个月至双线期,三个月有丝分裂后减数分裂开始,九个月只有核网期,青春期,每个月经周期一些卵母细胞发育,后期I,卵母细胞继续减数分裂,
3、中期 II,排卵,受精后卵母细胞完成减数分裂,出生时2.6102卵母细胞，大部分化,14天,胚胎6个月,3、Spermatogenesis and Oogenesis(精子和卵子的发生),2 meiosis,meiosis (减数分裂) ：Meiosis is the type of cell division by which germ cells (eggs and sperm) are produced，which occurs only in eukaryotes. Meiosis reduces genetic content and the number of chromosome
4、s to precisely half.（染色体数目减半的分裂） Meiosis comprises two successive nuclear divisions with only one round of DNA replication.,1. Characteristics of meiosis,1)、Meiosis comprises two successive nuclear divisions with only one round of DNA replication.（减数分裂的过程是DNA复制一次，细胞连续分裂两次）；2)、One parent cell produce
5、s four daughter cells. Daughter cells have half the number of chromosomes found in the original parent cell and with crossing over, are genetically different. （1 个母细胞分裂后形成 4 个子细胞，染色体数目减半）；3)、 Producing offspring that often differ greatly from either parent（子细胞与母细胞之间遗传性有较大差异。）,2.减数分裂的过程 Meiosis proce
6、ss,第一次分裂 第二次分裂,生长期,分裂期（前、中、后、末 ）,G1,S（只完成99.7%DNA复制）,G2,间期（不进行DNA复制）,分裂期（前、中、后、末 ）,1) . The first meiotic division减数分裂 I,间期,前期I(细线期),前期I(偶线期),1.同源染色体配对联会,2.二价体形成,前期I(粗线期),1.二价体四分体,2.非姐妹染色单 体之间出现交叉。,前期I(双线期),1.联会复合体消失,2.同源染色体某些部分分离,前期I(终变期),中期I,后期I,1.同源染色体分离（四分体二分体）,2.非同源染色体随机组合,间期,2) . The second me
7、iotic division减数分裂 II,前期 II,后期 II,1.姐妹染色单体分离（二分体单分体）,2.非姐妹染色单体随机组合。,末期 II,中期 II,3、 Significance of Mitosis,1）ensuring both genetic stability and genetic variability（保证了遗传物质的稳定性，又增加了变异性）；2）meiotic chromosome behavior change in the law of three major cellular basis of genetic （减数分裂是遗传三大定律的遗传学基础）,1）ens
8、uring both genetic stability and genetic variability,The pairing of homologous chromosomes during the first meiotic division Following meiosis，the process of crossing over，which occurs in the first meiotic prophase, reshuffles alleles between the maternal and paternal members of each homologous pair, which then segregate and assort independently into gametes. This results in the great amounts of genetic variation in gametes.,体细胞（2n）,
