What are the features of CRISPRa Stable Cell Lines? CRISPRa (CRISPR activation) system is a technology based on the improved CRISPR/Cas9 system that uses a synthetic programmable transcription factor to initiate endogenous transactivation of genes. In mammalian cells, the expressing of dCas9 (a nuclease-deficient Cas9 only retaining DNA binding activity) fused with a transcriptional activation domain, and gRNA complementary to the target promoter region in the genome, will result in increased transcription of the corresponding gene.

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The answer would be c, white eyes are homozygous recessive. in the early 1900s, morgan conducted several experiments with vinegar  flies (drosophila). one  sample revealed an anomaly: a  white-eyed, single male fly. he attempted to breed this fly with the typical red-eyed females. the offspring were all red-eyed. using flies from this new generation (brother-sister pairs)  produced some red-eyed and a few white-eyed flies. the white-eyed were all male. in later experiments, he was able to produce white-eyed females. this proved that white eyes are not lethal to either sex (ruling out a and b). since the percentage of white eyes to red eyes is so low, white eyes are not a dominant trait. it would be a recessive trait.