BI226 Chapter 5: Gene Linkage
Document Summary
Chapter 5 - linkage, recombination, and the mapping of genes on chromosomes. Linkage, recombination, and mapping of genes on chromosomes. Genes linked together on the same chromosome usually assort together. Detecting linkage by analyzing the progeny of dihybrid crosses: x linked genes. Synthetic genes - located on the same chromosome. Two x linked genes in drosophila with recessive alleles. W + (red eyes) and w (white eyes) Y + (brown body) and y (yellow body) F1 males get their only x chromosomes from their mothers. Compare allele configurations in f 2 to p generation. Deviation from 1:1:1:1 segregation in f 2 indicates the genes are linked. Note that in this cross involving x linked genes, only male progeny were counted the f. Designation of parental and recombinant relate to past history. Note that the parental configurations in these two crosses are opposite each other. Detect linkage by generating a double heterozygote and crossing to homozygous recessive (testcross)