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Gene Switches

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Fruit fly

Gene switches such as Ubx make the initial decisions of which genes to turn on or off in different body regions and cell types. Later in an animal's development, epigenetic switches take over. These epigenetic mechanisms act to maintain the fate of cells by doing what the Hox genes and other transcription factors did earlier, namely, controlling the "on" and "off" state of genes within each cell. This highly evolved, highly orchestrated ability to make genes active or inactive—both genetically and epigenetically—is the key to the success of multicellular plants and animals, including the most complex and mysterious of all, us.


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