Final answer:
The UAG, UAA, and UGA codons are recognized by termination factors, also known as release factors, which signal the end of protein synthesis and facilitate the release of the new polypeptide.
Step-by-step explanation:
The termination codons UAG, UAA, and UGA in mRNA are recognized by termination factors during protein synthesis. The process of translation concludes with the arrival of these stop codons, which signal to the ribosome that the polypeptide chain is complete. These termination factors, also known as release factors (RF1, RF2, and RF3), facilitate the release of the newly synthesized polypeptide chain from the ribosome. They are responsible for the hydrolysis of the bond between the polypeptide and the tRNA, allowing the polypeptide to be released, and subsequently enabling the dissociation of the ribosomal subunits from the mRNA.