分子生物学3chapter21.pptxVIP

we are approaching the 100th anniversary of the fruit fly as amodel organism for studies in genetics and developmental biology In 1908, Thomas Hunt Morgan and his research associates at Columbia University placed rotting fruit on the window ledge of their laboratory. 牛牛文库文档分享 牛牛文库文档分享Among the menagerie of creatures that were captured, the fruit fly emerged as the animal of choice.Study the inheritance of quantitative traits,such as eye k bottles ,using inexpensive yeast and agarthe fruit fly adults produced large numbers of progeny innjust two weeks 牛牛文库文档分享Drosophila Has a Rapid Life C 牛牛文库文档分享One of the key processes that occurs during larval development is the growth of the imaginal disksThe growth of the imaginal disks: arising from invaginations of epidermis in mid-stage embryos.imaginal disks differentiate into their appropriate adult structures during metamorphosis(or pupation,蛹化) 牛牛文库文档分享There is a pair of disks for every set of appendagesfor example ,a set of foreleg imaginal disks a set of antennae imaginal disks a set of mouthpart imaginal disks ------ Disks are composed of fewer than 100 cells in the embryo but ten thousands of cells in mature 牛牛文库文档分享Figure 21-16 Imaginal disks(器官芽) in D 牛牛文库文档分享The wing imaginal disk has become an important model system for the control of complex patterning processes by gradients of secreted signaling 牛牛文库文档分享The First Genome Maps Were Produced in DrosophilaIn 1910 the Morgan lab identified a spontaneous mutant male fly that had white eyes rather than the brilliant red seen for normal strains. This single fly lanched an incisive series of genetic studies --- led two major discoveries:Genes are located on chromosome Each gene is composed of two 牛牛文库文档分享Two allels assort independently during meiosis( Mendel’s first law )That genes located on separate chromosomes segregate independently (Mendel’s second law) Whreras those linked on the same chromosome do 牛牛文库文档分享Mendel’s first law: Genes are located on chromosom