实验二分离定律.ppt

1、实验二 分离规律的验证 一 原理 二 目的 观察糯质玉米和非糯质玉米杂种一代（F1）的花粉粒的分离现象，加深对分离规律的理解,掌握卡方检测的方法. 三 材料,种植非糯质(W xW x)和糯质(wxwx)两种基因型的玉米植株，待雄蕊抽出，即将开花前，套袋，于上午露水干时（约9：00左右），轻拍纸袋，收集花粉，另将上述两种基因型的玉米植株雌蕊套袋杂交（正交或反交）得F1种子，将F1种下，按上述方法收集花粉，干燥保存。,植物在减数分裂形成配子时，同源染色体上的等位基因必然随着染色体的分离而发生分离，互不干扰的分到不同的配子中去，形成带有不同基因的配子。基因的分离可以通过F1花粉粒某些性状的分离而观察

2、到。如水稻、玉米、高粱、谷子等作物的花粉粒中的淀粉，有糯性、非糯性之分。糯性含枝链淀粉多遇碘呈棕色，非糯性含较多的直链淀粉，遇碘呈蓝色。这是一对等位基因的差别，非糯(Wx)对糯性(wx)是显性。形成配子时，两种淀粉的花粉粒理论上数量相等。,四 步骤 用牙签（或大头针）沾取少量杂种一代（F1）花粉于干燥清洁的载片上，加1滴KI-I2液，混匀，加盖片，在低倍镜下（4*或10*）下区别糯质非糯质花粉粒色泽，按5点取样法统计F1花粉粒中糯质非糯质花粉粒的数目，总数不得少于200粒。 五 将所得结果填入下表，做X2测验，说明什么问题？,需要注意的几个问题？ 几个概念？ 等位基因 相对性状、显性性状、隐性

3、性状 正交、反交、测交、回交 自由度,光圈、染色时间、数量、放大倍数,孟德尔，G.J. Gregor Johann Mendel (18221884) 奥地利遗传学家,遗传学的奠基人。1822年7月22日生于奥地利的海因岑多夫（今捷克的海恩塞斯），1884年1月6日卒于布吕恩（今捷克的布尔诺）。他于1840年以优异的成绩毕业于特罗保的预科学校，即进入奥尔米茨哲学院学习。1843年因家贫而辍学；同年10月到奥古斯丁修道院做修道士。1847年被任命为神父。1849年受委派到茨纳伊姆中学任希腊文和数学代课教师。18511853年去维也纳大学学习物理学、化学、数学、动物学和植物学，在此期间受到著名物理

4、学家J.C.多普勒的数学和统计学的熏陶、植物学家F.J.A.N.翁格尔的物种可变和植物通过杂交可能产生新种观点的影响，这一切对他以后创造性的科学研究起了很大作用。1853年夏，他从维也纳大学毕业回修道院。1854年被委派到布吕恩技术学校任物理学和博物学的代理教师。他在那里工作了14年之久。,History,从18561863年，他进行了8年的豌豆杂交实验,并于1865年在布吕恩自然科学研究协会上报告了他的研究结果。1866年又在该会会刊上发表了题为植物杂交试验的论文。他在这篇论文中提出了遗传因子（现称基因）及显性性状、隐性性状等重要概念，并阐明其遗传规律,后人称之为孟德尔定律(包括“分离定律”

5、及“独立分配定律”)。孟德尔在实验中对于解决什么问题(亦即遗传规律)、选择什么材料和怎样分析结果,都有十分清晰的构思。他冲出了已往生物学界一直因循的活力论和目的论窠臼、敢于借鉴物理学中的粒子运动，即粒子的随机结合和分离作为实验设计分析的基点。在实验方法上一反前人笼统描述亲子间总合性状相似和不同的做法，把诸如茎杆高度、子叶颜色等作为各自独立的性状，并设想个体的总合性状乃是由多种独立性状随机组合和分离的产物。他的另一超人之处是在数据处理上没有忽视未表达所研究的独立性状的个体的数目。他所建立的测交法最能说明他对隐性个体遗传内涵的重视。但是这些发现当时并未受到学术界的重视。,The Major Wor

6、k of Gregor Johann Mendel - Experiments in Plant Hybridization, 1866,Ideas - The inheritance of characteristics is governed by pairs of discrete elements derived from each parent. - These parental elements pass into the germ cells of the offspring without influencing each other; this is the law of s

7、egregation. - The inheritance of one element does not govern the inheritance of any other element; this is the law of independent assortment.,Biography,1822 Born on 20 July (baptised on 22 July) in Hyncice, northern Moravia (then Austrian Silesia) to farmers, Anton and Rosina. 1831-1833 Elementary s

8、chool in Hyncice. In the autumn of 1833 Mendel moved to the Piarist school in Lipnik. 1834-1840 Gymnasium (grammar school) in Opava. Mendel helped pay his way by giving lessons to fellow students. 1840-1843 Institute of Philosophy in Olomouc. Mendels studies included mathematics, physics, philology,

9、 theoretical and practical philosophy and ethics. Augustinian Abbey in Old Brno. Mendel joined the Abbey as a novice under Abbot C. F. Napp (1792-1867) and assumed the name Gregor. Napp and the friar F. M. Klacel (1808-1882) are both thought to have profoundly influenced Mendels development as a sci

10、entist.,1845-1848 Institute of Theology (Brno). In 1846 Mendel completed a course in agricultural studies, apple and wine growing. 1847 Mendel is ordained priest. 1849-1851 Abbot Napp removed Mendel from his work in the parish on the grounds that it made him ill. He became a substitute teacher at th

11、e Gymnasium in Znojmo and at the Technical College in Brno. 1851-1853 University of Vienna. Mendel studied physics, mathematics and natural history and attended courses in “Experimental Physics” (Christian Doppler, 1803-1853), in “Anatomy and Physiology of Plants” (Franz Unger, 1800-1870), and in “P

12、ractical lessons in using the microscope”.,1854 Construction of the glasshouse in the Abbey garden. 1854-1868 Realschule (secondary modern school), Brno. Mendel taught physics and natural history. 1854-1864 Experimental work on garden peas. Mendel carried out experiments in plant hybridisation in th

13、e Abbey garden, with particular attention to Pisum sativum. He spent two years selecting Pisum lines with constant characteristics. 1861 Co-founder of the Natural Science Society in Brno. c. 1862 Mendel reads the German translation of the second edition (1860) of Darwins On the Origin of Species and

14、 makes notes in the margins. 1863 First publication on his meteorological observations. Mendel continued with these until 1882.,1865 Lectures on “Experiments in Plant Hybrids” at the February and March meetings of the Natural Science Society (Brno). In 1866, Mendel published his lecture, a work that

15、 was to establish him as “the father of genetics”. In the same year, he opened his correspondence with Carl Ngeli (1817-1891). 1868 Mendel became abbot after Abbot Napp, who had died in 1867. 1870 Publication of his experiments on Hieracium in Brno. 1871 Construction of the bee house in the Abbey ga

16、rden.,1872 Mendel was awarded the Cross of the Royal and Imperial Order of Franz Joseph I. 1881 Director of the Mortgage Bank of Moravia (Brno). 1884 Mendel died on 6 January. He was buried three days later in the Central Cemetery in Brno. His obituary in the Gesellschaft zur Frderung des Ackerbaues

17、, der Natur- und Landeskunde 1884, No. 1, said: “his experiments with plant hybrids opened a new era”.,Just before his death he commented: My scientific labors have brought me a great deal of satisfaction, and I am convinced that before long the entire world will praise the result of these labors. H

18、is serene confidence despite the lack of recognition his work received was to be vindicated. Mendel remains one of the great biologist of the nineteenth century and the inspiration for one of the most challenging sciences of our time - genetics.,孟德尔学说的遭遇给我们的启示？,stigma(柱头) Pistil style (花柱) ovary (子房

19、),分离规律的验证,一个正确的理论，不仅要能说明已经得到的试验结果，还应该能预测另一些试验的结果。,背景,达尔文的家养条件下动物和植物的变异（1868），德弗里的细胞内泛生论（1889），以及魏斯曼的种质论（1892）促进了人们对遗传问题的关注。德弗里和柯仑斯于1892年开展了系统性的杂交试验，1899年两人都发表了他们的异粉性（胚乳由花粉核形成，见Dunn，1966）试验的重要结果。,不久后干1900年春发生了一件生物学史上罕见的事，这似乎非常突然但实际上却是事态长期发展的一个高潮。有三位植物学家，德弗里、柯仑斯、丘歇马克，在短短几个月内先后发表文章声称他们分别独立地发现了重要的遗传定律，却不料在核查文献时才知道孟德尔已领先他们35年在19世纪60年代已经发现了这一定律。自此以后不断有人怀疑这三位植物学家的说法是否真实。这个问题看来至关重要，值得比较仔细地加以分析。,1865年，孟德尔在布鲁恩科学协会的会议厅，将自己的研究