4-18 differential gene expression

4-18 differential gene expression - balancer/balancer flies...

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DIFFERENTIAL GENE EXPRESSION 21.1 Geneticists Use Model Organisms That Are Genetically Tractable Drosophila as a Genetic Model Organism -good for genetic analysis b/c it is easy to grow and have a big genome (13,000 genes on 4 chromosomes), also matures quickly and each female fly produces 3000 offspring in her lifetime - balancer chromosome : researchers created these chromosomes by bombarding Drosophila with X rays, leading to multiple overlapping chromosomal inversions. The presence of multiple inversions prevents the recovery of crossover products balancer chromosome and its homologous normal chromosome remain as intact entities within the population w/no recombinant chromosomes passing to the progeny. Balancer chromosomes also have a dominant marker gene, which allows the visual identification of its presence. Balancer chromosomes contain a recessive lethal gene that prevents homozygous
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Unformatted text preview: balancer/balancer flies from surviving. The only offspring that survive matings of heterozygotes and wild-type homozygotes.-geneticists also use P element transposons that can move in and out of the Drosophila genome. They first insert a cloned gene of interest into the middle of the P element, which also contains a gene for visible characteristic (i.e. eye color). Next, they inject the recombinant P element DNA into eggs, along w/a helper plasmid that encodes the transposase gene. The transposase gene is transcribed and translated in the germ cells of the early embryo, enabling the recombinant P element bearing the gene of interest to insert itself into the embryos germ cell DNA. Progeny will express the eye color marker if the transformation plasmid was inserted into the parents germ cells....
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