连锁遗传及染色体作图课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,连锁遗传及染色体作图,连锁遗传及染色体作图,1,4.1 Law of Linkage (连锁规律,),Linkage is the tendency for alleles of two or more genes to pass from one generation to the next in the same combination. Only genes situated on the same chromosome can show linkage. That means the closer together any two genes lie on the same chromosome the more linkage they are to show linkage and the stronger that linkage will be.,连锁 - 两个或两个以上等位基因一起从一代传递到下一代的现象。,4.1 Law of Linkage (连锁规律)Linka,2,连锁遗传及染色体作图课件,3,连锁遗传及染色体作图课件,4,4.1.2 雌果蝇的不完全连锁遗传 (incomplete linkage)：,亲本 灰身残翅 (male) 黑身长翅 (female),子一代 灰身长翅(female) 黑身残翅(male),子代配子,配子比两两相等,测交后代,灰身残翅 灰身长翅 黑身残翅 黑身长翅,亲本型83%,41.5% 8.5% 8.5% 41.5% 交换型 17%,B,vg,B,vg,b,Vg,b,Vg,B,vg,b,Vg,b,vg,b,vg,B,vg,b,Vg,b,vg,B,vg,b,vg,b,Vg,b,vg,B,Vg,b,vg,B,Vg,b,vg,b,vg,b,vg,4.1.2 雌果蝇的不完全连锁遗传 (incomplete,5,连锁遗传及染色体作图课件,6,Incomplete linkage,同源染色体上的基因既有连锁又有交换的遗传现象,连锁互换律 presented in 1910 by Morgan,Incomplete linkage,7,4.2 Frequency of cross-overs (交换值),Frequency of cross-overs,=重组配子数,(交换型配子数),/ 总配子数,(交换型+亲本型),100%,= (No. of recombinant / Total no. of progeny) 100%,= 50%,= 0 50%,= 0,The closer the two genes are together the less likely it is that a cross-over will take place between them. The frequency of recombinants give an indirect measure of how close the two genes lie to each other.,*,发生交换的性母细胞比例为交换值的,?,倍,4.2 Frequency of cross-overs (,8,单交换(single cross-overs)：基因间分别发生单个交换,双交换(double cross-overs)：同源染色体上的等位基因间同时发生两次单交换。,图距：,If the recombination frequency is 14%, they have a map distance of 14 map units (图距) between them. 1% recombination is equivalent to 1 map unit. (1%的重组率等于1个图距),4.3 Mapping gene on chromosome,单交换(single cross-overs)：基因间分别发,9,Two-factor crosses (两点测验法),eg. Maize:,有色C / 无色c,饱满Sh / 凹陷sh,非糯性Wx / 糯性wx,Crosses are set out below:,Two-factor crosses (两点测验法),10,重组,有色、饱满(CCShSh),无色、凹陷(ccshsh),F1,CcShsh,无色、凹陷(ccshsh),C、Sh交换值3.6%,3.6 cM,重组有色、饱满(CCShSh) ,11,2. 糯性、饱满(wxwxShSh),非糯性、凹陷(WxWxshsh),F1,WxwxShsh,糯性、凹陷 (wxwxshsh),W、Sh交换值20%, 20 cM,2. 糯性、饱满(wxwxShSh) 非糯性、凹陷(WxW,12,|-23.6-|-20-|-3.6-|wx sh c,|-20-|-3.6-|-16.4-|sh c wx,|-23.6-,13,3. 非糯性、有色(WxWxCC),糯性、无色(wxwxcc),F1,WxwxCc,糯性、无色(wxwxcc),W、C 交换值22%，22cM,两值为什么不完全一致?,3. 非糯性、有色(WxWxCC) 糯性、无色(wxwx,14,Three-factor crosses (三点测验法): These are more accurate than two-factor crosses, in that they identify and utilize many of the double cross-overs that are missed by two-factor cross.,Three-factor crosses (三点测验法):,15,P,有色、饱满、非糯,(+ + + ) ,无色、皱缩、糯性,(cc shsh wxwx),F1,有色、饱满、非糯,(+c +sh +wx) 无色、皱缩、糯性(cc shsh wxwx),P 有色、饱满、非糯 (+ + + ),16,Phenotypes Genotypes no. of F2 assembled types,有色、饱满、非糯 + + + 2238 parental,无色、皱缩、糯性 c sh wx 2198,无色、饱满、非糯 c + + 98 single,有色、皱缩、糯性 + sh wx 107 cross-overs,有色、饱满、糯性 + + wx 672 single,无色、皱缩、非糯 c sh + 662 cross-overs,无色、饱满、糯性 c + wx 39 double,有色、皱缩、非糯 + sh + 19 cross-overs,Total no. of F2 6033,no. of F2 from double cross-overs： 39+19 = 58;,no. of F2 from single cross-overs I: 98+107 = 205;,no. of F2 from single cross-overs II: 672+662 = 1334,Phenotypes,17,Frequency of single cross-overs,= (no. of single cross-overs + no. of double cross-overs),/ total no. of progeny 100%,单交换值 = (单交换个体数+双交换个体数）/ 总数 100%,= 单交换值I + 双交换值,Frequency of single cross-over,18,Frequency of double cross-overs (双交换值 ),=(39+19) / 6033 100% = 0.96%,Frequency of single cross-overs I (单交换交换值),= (98+107) / 6033 100% + 0.96% = 3.4% + 0.96% = 4.36%,Frequency of single cross-overs II (单交换交换值),= (672+662) / 6033 100% + 0.96% = 22.11% + 0.96% = 23.07%,Map unit of C、Sh: 4.36 cM，Sh、Wx: 23.07 cM,I-27.43-I,I-4.36-I-23.07-I,C Sh Wx,Frequency of double cross-over,19,4.4 Interference（干涉）,：,交换在交叉处发生，一个单交换的发生，会影响另一个单交换的发生，即干涉。,双交换理论值=单交换值单交换值 =4.36% 23.7%=1%,The presense of one chiasmata in a particular chromosome region can reduce the frequency of others forming close to it. This can result in a reduction in the number of double cross-overs observed.,双交换实际值 双交换理论值 时 表明两个单交换间有干涉,4.4 Interference（干涉）：,20,Coefficient of coincidence （并发系数 S）：,T,he extent of interference is calculated as the coefficient of coincidence, the observed number of double cross-overs divided by the expected number of double cross-overs.,并发系数 S = 实际双交换值 / 理论双交换值,= 01 S ，干涉 ；,=1, single cross-overs independently, no interference;,=0, complete interference, no double cross-overs.,1-S = 干扰值,Coefficient of coincidence （并发,21,7 alleles Mendal researched,situated on 7 individual chromosome?,7 alleles Mendal researched,22,I II III IV V VI VII,A/a-0,I/i - 204,R/r - 60,Gp/gp - 21,V/v - 211,Le/le -199,F/f - 78,I II III,23,基因连锁群：,同一染色体上基因处同一连锁群，同类生物有n对染色体就有n个连锁群。,e.g.,Tomato 2n=24 12 linkage groups,Drosophila 2n=8 4 linkage groups,基因连锁群：,24,Application:,大麦 (barley) 高竿(B)/矮竿(b)，抗条锈病(T)/不抗条锈病(t),BT/BT bt/bt 两对基因连锁遗传，交换值为12%。,如何在F2代获得3-4株纯种矮竿抗病单株?,Application:,25,4.5 Linkage analysis in fungi (真菌的连锁分析):,Ascomycete (粗糙链孢霉):,Monoploid,and,sexual reproduction,- Good material for genetic analysis,Tetrad analysis (四分体分析): 减数分裂形成的四个线性排列的,子囊孢子 (ordered tetrad) 的分析,p112, p144,4.5 Linkage analysis in fungi,26,决定孢子颜色的基因和着丝粒间没有发生交换，被称为第一种分裂分离 (4:4的线性比),p112,决定孢子颜色的基因和着丝粒之间发生了交换，两种颜色 表型在第二次减数分裂时被分开，出现其他分离类型，称为第二种分裂分离 (2:2:2:2或2:4:2线性比),子囊中仅一半的孢子发生重组.,p113,In ascomycete fungi, first and second division segregation patterns can be used to determine distance between a gene and the centromere. A similar approach can be used to estimate distances between genes.,决定孢子颜色的基因和着丝粒间没有发生交换，被称为第一种分裂分,27,Recombinant frequency between gene and centromere,= ( no. of recombinant ascus / total no. of ascus ) 100% ,基因与着丝粒的重组率 =,交换型子囊数, 100% 1/2,总子囊数,Recombinant frequency between,28,eg.1 甲硫氨酸（-）的链孢霉菌株(,m,)与野生型(+)菌株杂交，基因与着丝粒间距多远? 做图表示交换型子囊 产生过程?,子囊数 孢子,1+2 3+4 5+6 7+8,6 +,m,+,m,5,m,+ +,m,6,m,+,m,+,7 +,m,m,+,40,m,m,+ +,36 + +,m,m,100,Centromere mapping: 着丝粒为基因座, 分析染色体上基因的,连锁关系及分布,eg.1 甲硫氨酸（-）的链孢霉菌株(m)与野生型(+,29,交换型子囊 24%，一半重组，基因与着丝点间距12cM,m,m,+,+,m,+,m,+,+,m,m,+,+,m,+,m,m,+,+,m,子囊数 6 5 6 7,子囊数 40/36,交换型子囊 24%，一半重组，基因与着丝点间距12cMmm+,30,