Question

(a) Explain the process by which amino acid gets attached to the tRNA molecule during translation process.
(b) How does the translation process get terminated?
(c) Expand ‘UTR’. Where are they located?

Hint:

(a) Aminoacyl-tRNA synthetase ensures that each tRNA molecule is charged with the correct amino acid before protein synthesis begins.
(b) The presence of a stop codon signals the end of translation, leading to the release of the polypeptide and termination of protein synthesis.
(c) The UTRs play a role in regulating translation efficiency and mRNA stability, but they are not translated into proteins.

Answer 1

(a) The amino acid is attached to the tRNA molecule by the enzyme aminoacyl-tRNA synthetase. The enzyme binds the appropriate amino acid to the corresponding tRNA molecule, ensuring that the tRNA carries the correct amino acid for protein synthesis. This process requires ATP.
(b) Translation terminates when a stop codon (UAA, UAG, or UGA) is encountered in the mRNA sequence. Release factors bind to the stop codon, causing the ribosome to release the newly synthesized polypeptide and dissociate from the mRNA.
(c) UTR stands for Untranslated Region. UTRs are regions in the mRNA that are transcribed but not translated into proteins. There are two types: 1. 5’ UTR: Located before the start codon. 2. 3’ UTR: Located after the stop codon.