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Multiple Choice
The P site of a ribosome does which of the following?
A
It holds the tRNA that is carrying the next amino acid to be added to the growing polypeptide chain.
B
It helps "unzip" DNA during transcription.
C
It catalyzes the addition of amino acids to the tRNAs.
D
It holds the tRNA carrying the growing polypeptide chain.
Verified step by step guidance
1
Understand the role of the ribosome in protein synthesis: Ribosomes are the molecular machines in the cell that facilitate the translation of mRNA into a polypeptide chain, which will eventually fold into a functional protein.
Identify the different sites on the ribosome: The ribosome has three key sites known as the A (aminoacyl), P (peptidyl), and E (exit) sites. Each site plays a specific role during translation.
Clarify the function of the P site: The P site, or peptidyl site, is responsible for holding the tRNA that carries the growing polypeptide chain. This is where the peptide bond formation occurs, linking the new amino acid to the chain.
Differentiate the P site from other sites: The A site holds the tRNA carrying the next amino acid to be added, while the E site is where the tRNA exits the ribosome after its amino acid has been added to the chain.
Conclude with the correct function: Based on the roles of the ribosomal sites, the P site specifically holds the tRNA carrying the growing polypeptide chain, which is crucial for the continuation of protein synthesis.