Answer to Question #189910 in Molecular Biology for Misbah

Question

A terminator acts as a termination signal in the process of transcription, whereas termination of translation is brought about by a stop codon. How the terminator and stop codon differ from each other with regards to ending the process in which they are involved? Give an answer comprising at most 2 sentences.

Answer 1

Termination is the ending of transcription, and occurs when RNA polymerase crosses a stop (termination) sequence in the gene. The mRNA strand is complete, and it detaches from DNA.

Termination of translation occurs when a nonsense codon (UAA, UAG, or UGA) is encountered on a mRNA strand. Upon aligning with the A site, these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that instruct peptidyl transferase to add a water molecule to the carboxyl end of the P-site amino acid. This reaction forces the P-site amino acid to detach from its tRNA, and the newly made protein is released.

Answer:

The termination sequence (terminator) is located on the DNA strand. It signals for the end of transcription and the separation of the RNA polymerase and the mRNA strand. The stop codon, located on the mRNA strand, represents the end of a certain gene.