遗传学Chapter07 Linkage and Chromosome Mapping in eukaryotyes.ppt

制作：罗培高,1/42,Preface,AS we well know genotype determined phenotype in all organism.,制作：罗培高,2/42,Segregation law,During gametes and zygotes formations, what rule do genes comply with when they transmit from parental generation to the next generation. Because a pair of alleles is located on a homologous pairs of chromosomes in diploid biology, alleles as well as homologous chromosomes is segregated in meiosis due to chromosomes as vectors of genes. Note: this is common law describing the behavior of alleles.,制作：罗培高,3/42,Segregation law,制作：罗培高,4/42,Chapter 7 Linkage and chromosome mapping in eukaryotes,Many genes reside on each chromosome. Unless they are separated by crossing over, alleles at the loci on each homolog segregate as a unit during gamete formation. Recombinant gametes resulting from crossing over enhance genetic variability within a species and serve as the basis for constructing chromosome maps.,制作：罗培高,5/42,Main content,1 Linkage versus independent assortment 2 Incomplete linkage 3 Mapping in Drosophila and maize 4 The accuracy of mapping experiments 5 Somatic cell hybridization and human gene mapping 6 Molecular markers and annotated database 7 Haploid organisms in linkage and mapping studies. 8 Other aspects of genetic exchange 9 Did Mendel encounter linkage?,制作：罗培高,6/42,Section 7.1 Linkage versus independent assortment,Because chromosomes contains a very large number of genes, and the chromosome, not the gene, is the unit of transmission during meiosis, genes on the same chromosome are not free to undergo independent assortment.,制作：罗培高,7/42,Independent assortment,制作：罗培高,8/42,Complete linkage,制作：罗培高,9/42,Incomplete linkage,制作：罗培高,10/42,Linkage inheritance,Linkage inheritance: is the tendency of genes located in the same chromosome to be associated in inheritance. Linked genes have their loci along the same chromosome, do not assort independently, but can be separated by crossing over. Complete linkage produces only parental or non-crossover gametes. Incomplete linkage produces this exchanged gamete, called recombinant or crossover gametes.,制作：罗培高,11/42,制作：罗培高,12/42,The linkage ration,制作：罗培高,13/42,Linage groups,Linkage groups is a group of gene that have their loci on the same chromosome. In a species, there are as many linkage groups as there are homologous pairs of chromosome or as the haploid number of chromosomes.,制作：罗培高,14/42,Suggestion,Two genes located relatively close to each other along a chromosome are less likely to have a chiasma form between them than if the two genes are farther apart on the chromosome. Therefore, the closer two genes, the less likely a genetic exchange will occur between them.,制作：罗培高,15/42,Cross experiment of two pairs of contrasting traits of pea (Lathyrus odoratus),Cross experiment of two pairs of contrasting traits of pea (Lathyrus odoratus) flower color: purple (P) dominant versus red (p) recessive Pollen grain shape: long (L) dominant versus round (l) recessive 1. Purple and long (PPLL)red and round (ppll) 2. Purple and round (PPll)red and long (ppLL),制作：罗培高,16/42,Purple and long (PPLL)red and round (ppll),制作：罗培高,17/42,Purple and long (PPLL)red and round (ppll),Results： Phenotypes of F1 are dominant，four phenotypes of F2; The ratio of four phenotype of F2is different of classic ratio of 9:3:3:1， two parental phenotypes are higher than theory number，and two combined phenotypes are less than theory number.,制作：罗培高,18/42,Purple and round (PPll)red and long (ppLL),制作：罗培高,19/42,Purple and round (PPll)red and long (ppLL),Results： Phenotypes of F1 are dominant，four phenotypes of F2; The ratio of four phenotype of F2is different of classic ratio of 9:3:3:1， two parental phenotypes are higher than theory number，and two combined phenotypes are less than theory number.,制作：罗培高,20/42,Coupling phase and repulsion phase,Coupling（相引） phase: Allelic arrangement in which mutant are on the same chromosome and wild-type alleles are on the homologue. Repulsion （相斥）phase: allelic arrangement in which each homologous chromosome has mutant and wild-type alleles. coupling phase versus repulsion phase,制作：罗培高,21/42,Explanation of linkage inheritance,Why the ratio of F2 is different from the classic ratio of 9:3:3:1： Is the separation law fit to a pair of gene? Is the independent law fit to non-allelic genes?,制作：罗培高,22/42,Purple and long (PPLL)red and round (ppll),制作：罗培高,23/42,Purple and round (PPll)red and long (ppLL),制作：罗培高,24/42,Separation law is fit to the allelic gene in the two experiment,制作：罗培高,25/42,Independent assortment law test?,制作：罗培高,26/42,Independent assortment law test?,制作：罗培高,27/42,Test cross: coupling phase,制作：罗培高,28/42,Test cross: repulsion phase,制作：罗培高,29/42,Results of test cross,The four gametes produced by F1do not equal to the ratio of 1:1:1:1； Parental gamete number is higher than 50，and the combined gamete number is less than 50； Parental gametes is with even number，and combined gametes is also with even number.,制作：罗培高,30/42,Cross Experiment of Drosophila (couplin。