Where does the energy come from to add a uracil to the 3' end of a transcript?
A)the energy released by allowing the uracil to complementary base pair with an adjacent thymine
B)the hydrolysis of a terminal phosphate from the incoming UTP molecule
C)the cell's supply of ATP
D)the hydrolysis of pyrophosphate from the incoming UTP molecule
E)the hydrolysis of all three phosphate groups from the incoming UTP molecule

Question

Quizplus · Accepted Answer

The hydrolysis of pyrophosphate from the incoming UTP molecule provides the energy required to add a uracil to the 3' end of a transcript. This is because the breaking of the phosphate bond releases energy, which can be used to drive an endergonic reaction such as this one. Option A is incorrect because thymine is not involved in this process. Option B is incorrect because UTP is the incoming nucleotide, not a terminal phosphate molecule. Option C is incorrect because ATP is not directly involved in this process. Option E is incorrect because the hydrolysis of all three phosphate groups from the incoming UTP molecule would release too much energy and could potentially damage the RNA molecule.

Where Does the Energy Come from to Add a Uracil