Question

The changing or activation of a tRNA molecule includes:

Group of answer choices

A. the covalent attachment of the carboxyl group of an amino acid to the tRNA.

B. the covalent attachment of the amino group of an amino acid to the tRNA.

C. the covalent attachment of an amino acid to the 3' terminal cytosine of the tRNA.

D. the covalent attachment of an amino acid to the 5' terminal adenosine of the tRNA.

Answer 1

Answer - C. the covalent attachment of an amino acid to the 3' terminal cytosine of the tRNA.

tRNA contain a CCA tail made up of cytosine-cytosine-adenine sequence at the 3’ end. Amino acid attached here with help of tRNA ligase to form aminoacyl-tRNA. Amino acid is covalently bonded to the 3' hydroxyl group on the CCA tail of tRNA.

This is catalyzed by the enzyme tRNA-ligase that attaches appropriate amino acid to tRNA that is also called the loading or charging of tRNA with amino acid. Once it is charged ribosome can transfer amino acid from tRNA to growing poly-peptide chain.