24. 請問丑角染色體(Harlequin chromosome)是下列何種現象之證明？
(A) 雙重染色體互換(double crossover)
(B) 基因轉換(gene conversion)
(C) 減數分裂式重組(meiotic recombinant)
(D) 姐妹染色分體交換(sister chromatid exchange)

Harlequin chromosomes are characterized by differential staining of the two sister chromatids of a chromosome.

A chromatid of a harlequin chromosome may have both dark- and light-stained regions due to a reciprocal exchange between sister chromatids. The number of such sister chromatid exchanges (SCEs) per cell can vary considerably and may be a sign of a heritable disease, like Bloom's or Werner's syndrome, or exposure of cells to radiation or genotoxic compounds.