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Multiple Choice
When a ribosome reaches a stop codon during translation, what occurs?
A
The ribosome incorporates a stop amino acid into the polypeptide.
B
The ribosome releases the newly synthesized polypeptide chain.
C
The ribosome continues adding amino acids beyond the stop codon.
D
The ribosome moves back to the start codon to begin translation again.
Verified step by step guidance
1
Understand the process of translation: Translation is the process by which ribosomes synthesize proteins using mRNA as a template. It involves three main stages: initiation, elongation, and termination.
Identify the role of stop codons: Stop codons (UAA, UAG, UGA) are specific sequences in the mRNA that signal the end of translation. They do not code for any amino acid.
Explain what happens when a stop codon is reached: When the ribosome encounters a stop codon, no tRNA with a complementary anticodon exists to bind to it. Instead, release factors (proteins) bind to the stop codon.
Describe the action of release factors: Release factors trigger the ribosome to release the newly synthesized polypeptide chain from the tRNA in the P site. This marks the end of protein synthesis.
Conclude the process: After releasing the polypeptide, the ribosome disassembles into its subunits, and the mRNA is released. The ribosome does not incorporate a stop amino acid, continue adding amino acids, or move back to the start codon.