Question

Refer back to the figure of the intron in the previous question. Imagine that there is a U1 snRNA mutation in which the sequence "cau" (locate this by finding the highlighted central a), is mutated to "gua". Which of the following is NOT a consequence of this mutation? O The mRNA will not be exported from the nucleus to the cytosol The mRNA will be 135 bases longer than it should be O The mRNA will encode a protein that is 45 amino acids longer than the wildtype protein The U1 snRNA will not properly recognize the 5' splice site

Answer 1

The fourth option is correct answer. Because the U1 snRNA has a conserved sequence for the recognition of 5’ splicing site, in the mutation of cau to gua sequence must not make able the u1 snRNA to recognize the splicing site. The 5’ splicing site must have GU sequence and the snRNA through its complementary CA sequence gets able to bind there. Here the snRNA has GU sequence, which is not complementary. Therefore, it cannot bind to the splicing site.

Answer- 4^th option