Which codons are recognized as stop codons in protein synthesis?

The correct answer identifies UAA, UAG, and UGA as stop codons in the genetic code. Stop codons play a crucial role in the process of protein synthesis by signaling the termination of translation. When the ribosome encounters one of these codons during the elongation phase of protein translation, it recognizes that the polypeptide chain is complete. Consequently, this causes the release factors to bind and promote the disassembly of the ribosomal complex, ultimately releasing the newly synthesized protein.

In the context of your other choices: AUG is known as the start codon because it is the first codon in the mRNA sequence that initiates translation, coding for methionine. GGU codes for glycine, which is an amino acid that contributes to protein synthesis but does not function as a stop signal. ACG codes for threonine, another amino acid involved in protein synthesis but not relevant to termination. Thus, the function of the stop codons in terminating protein synthesis is what makes UAA, UAG, and UGA specifically significant in the process.