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felipebelt felipebelt
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Posts: 332
3 years ago
Rhodobacter cells perform photosynthesis in the presence of light and grow heterotrophically in the dark. After being cultured in total darkness for multiple generations, phenotypic and genotypic changes occur. What phenotypic changes occur and what evolutionary processes are driving them?
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Fifagirl101Fifagirl101
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Posts: 213
3 years ago
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 When a population of phototrophs is grown in the dark for multiple generations, the population will tend to lose the ability to produce photopigments and may even lose the ability to perform photosynthesis altogether. This occurs because there is no selection for the production of the pigments and enzymes necessary for photosynthesis. The production of photosynthetic pigments and enzymes is metabolically expensive, thus producing them when they are not needed results in a competitive disadvantage in the dark cultures, thus random mutants that produce fewer pigments take over Rhodobacter cultures grown in the dark. The evolutionary processes behind this phenotypic change are random mutations to the genome, followed by the selection of mutants that grow better in the dark.
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