Question

Aminoacyl -tRNA snythetases: Which of the following is true about aminoacyl-tRNA synthetases?

1) Family of enzymes that synthesize tRNAs
2) Enzymes responsible for transport of tRNAs to the ribosome
3) Family of enzymes which attach amino acids to tRNA
4) Enzymes that add amino acid attachment sites to newly synthesized tRNAs
5) Enzymes that degrade tRNAs which have already added their amino acid

Answer 1

Aminoacyl-tRNA synthetases are enzymes that attach amino acids to their corresponding tRNA molecules, a process called 'charging' the tRNA. This step is essential for protein synthesis, ensuring that each tRNA carries the correct amino acid as dictated by the mRNA codon. There exists at least one specific synthetase for each of the 20 amino acids.

Step-by-step explanation:

Aminoacyl-tRNA synthetases are a family of enzymes crucial for protein synthesis. Their main function is to charge tRNA molecules, a process that involves adding an amino acid to each tRNA corresponding to the genetic code. Specifically, option 3) Family of enzymes which attach amino acids to tRNA is true about these enzymes.

The process begins with the enzyme binding and hydrolyzing ATP to catalyze a high-energy bond between the amino acid and adenosine monophosphate (AMP); this results in the release of a pyrophosphate molecule. The next step is the transfer of the activated amino acid to the tRNA, after which AMP is released, thereby charging the tRNA. Each tRNA is now 'charged' and carries the amino acid specific to the codon it will match on the mRNA during protein synthesis.

Overall, aminoacyl-tRNA synthetasesensure that each tRNA carries the correct amino acid, maintaining the fidelity of protein translation. This specificity is achieved because there is at least one type of aminoacyl-tRNA synthetase for each of the 20 amino acids found in proteins.