White eyes in Drosophila melanogaster result from an X‑linked recessive mutation. Occasionally, white‑eyed mutants give rise to
offspring that possess white eyes with small red spots. The number, distribution, and size of the red spots are variable. Explain how a transposable element, or transposon, could be responsible for this spotting phenomenon. Excision of a transposable element out of the eye color locus during eye development produces a patch of cells that produce red pigment. A transposable element is introduced into the regulatory region of the eye color gene and causes gene expression to be reduced, which results in white eyes with red spots. Insertion of a transposon upstream of the eye color locus during eye development activates the red pigment production gene in a patch of eye cells. A transposon located within the eye color gene uses reverse transcriptase to produce the normal gene product, which causes white eyes with red spots. Transposable elements insert into the eye color locus in the majority of the eye cells, leaving only a patch of eye cells with an active eye color locus that produces red pigment.
The response is the following statement "Transposable elements insert into the eye color locus in the majority of the eye cells, leaving only a patch of eye cells with an active eye color locus that produces red pigment"
Explanation:
Transposable elements (TEs) were originally referred to as jumping genes because they have the potential to be inserted in different genomic regions. TE insertions often occur randomly and thus may affect the phenotype of individual cells in a tissue, a genetic phenomenon called variegation
Answer: A transposable element is introduced into the regulatory region of the eye color gene and causes gene expression to be reduced, which results in white eyes with red spots
