7. Andrew Fire, Craig Mello, and their colleagues were among the first to examin

Question

7. Andrew Fire, Craig Mello, and their colleagues were among the first to examine the effects of double-stranded RNA on gene expression (A. Fire et al. 1998. Nature 391:806-811). In one experiment, they used a transgenic strain of C. elegans into which a gene (gfo) for a green fluorescent pigment had been introduced. They injected some worms with double-stranded RNA complementary to coding sequences of the gfp gene and injected other worms with double-stranded RNA complementary to the coding region of a different gene (unc22A) that encodes a muscle protein. The photographs on the next page show larvae and adult progeny of the injected worms. Green fluorescent pigment appears as bright spots in the photographs. (1 pt) randed Double-stranded gfp RNA unc22A RNA A. Explain these results. Larvae Adult Fire and Mello conducted another experiment in which they injected double-stranded RNA complementary to the introns and promoter sequences of the gfp gene. What results would you expect with this experiment? Explain your answer. B.

Explanation / Answer

A. In this experiment Andrew fire and Craig mello had injected worms either with double stranded RNA coplimentary to the coding region of unc22A gene and GFP gene. When double stranded RNA against a coding region of gene unc22A is introduced, it silence the effect of the gene, so thus the unc22A protein is no longer expressed. As a result the adult worm will showed a distorted movement pattern. In the second set they used GFP reporter protein. When double stranded RNA against GFP gene is introduced, it also inhibit the expression of GFP gene which can then be seen only as a bright spot on the adult.

Thus this experiment showed that double stranded RNA against the coding regions of gene can silence the expression of the partcular gene, so the genes are no longer functional.

B. If double stranded RNA is injected against the intron and promoter sequence of GFP gene , it will show no effect, As double stranded RNA is functional only on silecing coding regions, means they are woking on postranscriptional machinary. As introns or promoter sequence of GFP do not code for anyprotein, double stranded RNA will not have any effect.

Related Questions

Navigate

• Browse (All)
• Browse 7
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.