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Gene Expression, Function, and Regulation RS: Maribel Alvarez April 9, 2011 What do this characters have in common? They are mutants What is a mutant? An organism whose DNA has been changed. These changes cause the organism to display new characteristics or traits not found in wild-type. Wild-type (Typical form found in a population) Mutant Scientist make mutant animals to study gene function and their products ~19,000 genes 40% found in humans ~40,000 genes Almost all genes are also found in humans ~14,000 genes 50% found in humans Gene Expression Gene Expression x x How is the organism affected by the loss of this gene/protein? What role does the gene/protein have in the organism. • The development and growth of an organism is greatly dependent on the proper expression of genes QuickTime™ and a decompressor are needed to see this picture. Human mutations results in medical conditions Aniridia: Sickle cell anemia: Pax6 Hemoglobin Primordial Dwarfism: Androgenic alopecia (baldness): PCNT Androgen receptor(AR) How does an organism know when and where a gene is required to be on? How does your body know when to turn on Pax 6 to make your eyes? How does you body know only to turn on Pax 6 in cell located forehead and nose? Why don’t you develop eyes on your arm or legs? Trancription factors are proteins that bind to regions of DNA to switch on genes in specific regions at a specific time. They regulate gene expression. Organisms need genes expressed in specific cells at the right time. Gene expression must be regulated for proper growth and development of organisms • All cells have the same genetic information however only specific genes are turned on or expressed in each cell type QuickTime™ and a decompressor are needed to see this picture. Gene expression, function, and regulation • 1. What would happen if the neuron specific gene is not expressed in cell one? No neuron 1. •2. What would happen if the neuron specific gene was expressed instead of the epithelial specific gene in cell 2? The cell that was suppose to be an epithelial cell would be a neuronal cell. 2. QuickTime™ and a decompressor are needed to see this picture. Decapentaplegic(Dpp) is a TGF-β ligand (protein) important for wing growth and development in Drosophila Dpp expression wing disc What do you think would happen to the wing if there is a mutation that would prevent Dpp expression (Can not be turned on)? Adult wing What do you think would happen to the wing if Dpp is suddenly turned on in cells that usually do not express or need Dpp for wing development? BMP4 is the human homolog of Dpp Drosophila Humans Function Dpp BMP4 Both required for the early differentiation of the embryo and establishing of a dorsal-ventral axis QuickTime™ and a decompressor are needed to see this picture. Fibrodysplasia ossificans progressiva is a disease due to high levels of BMP4. 75% of human disease genes are also found in flies