In the early 1990s, Carolyn Napoli and her colleagues were working on petunias, attempting to genetically engineer a variety with dark purple petals by introducing numerous copies of a gene that encodes purple pigment in the flower petals . Their thinking was that extra copies of the gene would cause more purple pigment to be produced and would result in a petunia with an even darker hue of purple. However, much to their surprise, many of the plants carrying extra copies of the purple gene were completely white or had only patches of color. Molecular analysis revealed that the amount of mRNA produced by the purple gene was reduced 50-fold in the engineered plants compared with wild-type plants. Somehow, the introduction of extra copies of the purple gene silenced both the introduced copies and the plant’s own purple genes. Provide a possible explanation for how the introduction of numerous copies of the purple gene silenced all copies of the purple gene.

In the early 1990s, Carolyn Napoli and her colleagues were working on petunias, attempting to genetically engineer a variety with dark purple petals by introducing numerous copies of a gene that encodes purple pigment in the flower petals . Their thinking was that extra copies of the gene would cause more purple pigment to be produced and would result in a petunia with an even darker hue of purple. However, much to their surprise, many of the plants carrying extra copies of the purple gene were completely white or had only patches of color. Molecular analysis revealed that the amount of mRNA produced by the purple gene was reduced 50-fold in the engineered plants compared with wild-type plants. Somehow, the introduction of extra copies of the purple gene silenced both the introduced copies and the plant’s own purple genes. Provide a possible explanation for how the introduction of numerous copies of the purple gene silenced all copies of the purple gene.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter13: An Introduction To Genetic Technology

Section: Chapter Questions

Problem 3CS

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In the early 1990s, Carolyn Napoli and her colleagues were working on petunias, attempting to genetically engineer a variety with dark purple petals by introducing numerous copies of a gene that encodes purple pigment in the flower petals (C. Napoli, C. Lemieux, and R. Jorgensen. 1990. Plant Cell 2:279–289). Their thinking was that extra copies of the gene would cause more purple pigment to be produced and would result in a petunia with an even darker hue of purple. However, much to their surprise, many of the plants carrying extra copies of the purple gene were completely white or had only patches of color. Molecular analysis revealed that the amount of mRNA produced by the purple gene was reduced 50-fold in the engineered plants compared with wild-type plants. Somehow, the introduction of extra copies of the purple gene silenced both the introduced copies and the plant’s own purple genes. Provide a possible explanation for how the introduction of numerous copies of the purple gene…
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