In order to attach a particular amino acid to the tRNA molecule ...

[Hawke]

In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?
A) The ATP must first have to attach to the tRNA.
B) The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme.
C) The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase.
D) The tRNA molecule must have to alter its shape in order to be able to fit into the active site with the other two molecules.
E) The 3' end of the tRNA must have to be cleaved before it can have an attached amino acid.

[coco]

Pick B. 100% sure!