PPT-LINKAGE If the genes are situated in the same chromosome and are fairly close to each

SUTTONS 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. 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 . Contents:. Introduction to sex linked inheritance.. Chromosome carries which type of genes?. Three types of traits. Characteristics of sex linkage.. Types of sex linkage.. Sex linked disorders.. Sex linked inheritance :. 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. Linkage. One of the main observations from Mendel was independent assortment – alleles of different genes will get assorted (mixed up) independently of one another. We already showed that the genes are carried by the linear chromosomes. 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. 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 . (. 2. ).. A relative Distance . between linked genes . on chromosome. . Also, Provides . clues about which chromosome contains the gene and . precisely where the gene lies . on that chromosome.. Chromosome mapping can . 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. 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.. UNIT


 \t\n\f\f\r\f\t\t\n\f\f\r\f\t cation of marker-trait associations, mapping Quantitative Trait Loci (QTL), candidate gene identi cation, basis for high-resolution genetic ne-mapping, which provide powerful tools for genetic anal Discovery. Genetic linkage was first discovered by the British. . geneticists William Bateson, Edith Rebecca Saunders and Reginald Punnett. . shortly after Mendel's laws were rediscovered. The understanding of genetic linkage was expanded by the work of Thomas Hunt Morgan. . 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.. 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..