PPT-Sex Linkage and Lethal Genes

Sex determination Sex in mammals is determined by two chromosomes known as the sex chromosomes or heterosomes Females XX are the homogametic sex Males XY are the heterogametic sex. Prepared by -. RAKESH CHOUDHARY. M.Sc.(AGRI) . GENETICS AND PLANT BREEDING . . WELCOME. Linkage and Chromosome. Mapping . Linkage and Chromosome. Mapping . Genetic linkage was first discovered by the . Trey Ideker. Genetics 101:. The Basis of Genome Association. Selected slides courtesy. Jim . Stankovich. and Hector . Corrada. Bravo. Review of Mendelian genetics. Gregor Mendel analyzed the patterns of inheritance of seven pairs of contrasting traits in the domestic pea plant. As an example pair:. Patterns of inheritance. Homework - Multiple Alleles: Hierarchy. Sometimes there are more than 3 alleles, occurring in a dominance hierarchy. Coat Colour in Rabbits. Agouti coat is dominant to Chinchilla coat, which is dominant to Himalayan coat, which is dominant to Albino coat. Inheritance of genes that are on different chromosomes vs. close together on the same chromosome. When genes are closely linked on the same chromosome, how does this affect their segregation pattern?. The Chromosome Theory of Heredity. Mutations. Regulation of Gene Expression. Objectives. State the chromosome theory of heredity. Explain how gene linkage affects inherited traits. Describe the process of crossing-over and explain how it increases genetic variety. Mendel’s . Law of Independent Assortment. Autosomal linkage. Genes that do not obey Mendel’s Law of Independent Assortment. Linked genes. Linkage is the tendency for a group of genes, on the same chromosome, to be inherited together. Patterns of inheritance. Homework - Multiple Alleles: Hierarchy. Sometimes there are more than 3 alleles, occurring in a dominance hierarchy. Coat Colour in Rabbits. Agouti coat is dominant to Chinchilla coat, which is dominant to Himalayan coat, which is dominant to Albino coat. Mendel’s traits showed two distinct forms . Most genes do not exhibit simple inheritance. Genotypic ratios persist but phenotypic ratios may vary due to “outside-the-gene” influences including . PBG 430. Linkage. Linkage is the non-random . association. of two or more phenotypes or sequences in a population (genes/sequences are (almost) always inherited together). Biological explanation for linkage: genes or sequences are closely located in the same chromosome. KEY CONCEPT . Genes can be mapped to specific locations on chromosomes.. . Discovery education. http://app.discoveryeducation.com/player/?assetGuid=4FAF6391-FD45-4249-A188-66C3DF02770F&fromMyDe=0&isPrinterFriendly=0&provider=&isLessonFromHealth=0&productcode=US&isAssigned=false&includeHeader=YES&homeworkGuid. SUTTON’S VIEW ON LINKAGE:. Sutton predicted that the chromosomes are the bearers of the units of heredity or genes and since the number of hereditary units is much larger than the number of chromosomes, therefore each chromosome must contain a number of genes.. As there are more genes than chromosomes, it can be expected that each chromosome contains more than one gene.. The genes for different characters may be either situated on the same chromosome or on different chromosome.. syntenic. genes. The genes located on the same chromosome are called . syntenic. genes.. When the . syntenic. genes are as close physical association on chromosome to one another preventing independent assortment or c.o. and are being inherited together are known as linked genes.. M.Sc. II semester. Paper –III, Unit 4. By . Dr. . Tulika. . Mishra. LINKAGE. Genetic linkage. is the tendency of . DNA sequences. that are close together on a . chromosome. to be inherited together during the .