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Use the following information to answer the question.

A transfer RNA (#1) attached to the amino acid lysine enters the ribosome. The lysine binds to the growing polypeptide on the other tRNA (#2) in the ribosome already.
Which component of the complex described enters the exit tunnel through the large subunit of the ribosome?
A. initiation and elongation factors
B. tRNA that no longer has attached amino acid
C. newly formed polypeptide
D. tRNA with attached lysine (#1)
E. tRNA with polypeptide (#2)

User Melynda
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2 Answers

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Final answer:

The tRNA with polypeptide (#2) enters the exit tunnel through the large subunit of the ribosome during translation elongation.

Step-by-step explanation:

The component of the complex described that enters the exit tunnel through the large subunit of the ribosome is tRNA with polypeptide (#2). During translation elongation, the ribosome translocates in the 5' to 3' direction of the mRNA, and the tRNA with the growing polypeptide chain moves from the A site to the P site. The previous tRNA, which is now empty, enters the E site and is expelled from the ribosome.

User Curt Nelson
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7 votes

Final answer:

The newly formed polypeptide is the component that enters the exit tunnel through the large subunit of the ribosome after the tRNA (which was initially in the P site) with the attached growing peptide chain moves to the E site and is expelled without an amino acid.

Step-by-step explanation:

In the given scenario where a tRNA attached to the amino acid lysine enters the ribosome and binds to the growing polypeptide on the other tRNA already present in the ribosome, the component of the complex described that enters the exit tunnel through the large subunit of the ribosome is the newly formed polypeptide. After a peptide bond is formed, the tRNA that held the growing polypeptide chain (tRNA #2) shifts from the A site to the P site in the ribosome, and then as the ribosome continues to advance, this tRNA moves to the E site where it loses its amino acid attachment and is eventually expelled, leaving the ribosome.

The process of translation elongation includes the ribosome moving one codon at a time, allowing a charged tRNA to enter at the A site, the formation of a peptide bond between the amino acid at the A site and the growing polypeptide chain at the P site, followed by the moved tRNA without an amino acid to exit the E site. This cycle repeats as the newly formed polypeptide chain is elongated.

User Adi Inbar
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