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The centromeric dodeca - satellite of Drosophila forms altered DNA structures in vitro in which its purine - rich strand ( G - strand ) forms stable fold - back structures , while the complementary C - strand remains unstructured .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
Answer:
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