This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Translation, Subject name: Biochemistry
In translation process , proof reading of mRNA is done by : 
Select and explain. 
A. RNA polymerase, B. Amino - acyl-t - RNA synthetize, C. Leucine zipper, D. DNA
B: Amino - acyl-t - RNA synthetize
Answer: B: Amino - acyl-t - RNA synthetize 
Explanation: Ans. is 'b' Amino acyl-t- RNA synthetase : Aminoacyl - tRNA synthetase :"This family of enzymes is required for attachment of amino acids to their corresponding tRNAs. Each member of this family recognized a specific amino acid and the tRNA that correspond to that amino acid. Each amino acyl - tRNA synthetase catalyzes a two-step reaction that results in the covalent attachment of an amino acid to its corresponding tRNA . The extreme specificity of the synthetase in recognising these two structures is largely responsible for the high fidelity of translation of the genetic message". - Lippincott, 2/e.