Question

The ER signal sequence on a growing polypeptide chain is recognized by a signal

recognition particle (SRP) in the cytosol. This interaction:
A. causes the polypeptide chain to dissociate from the ribosome.
B. causes the ribosome to return to the pool of free ribosomes in the cytosol.
C. guides the ribosome and its polypeptide to the ER membrane.
D. speeds the synthesis of the polypeptide chain.

Answer 1

The interaction between the ER signal sequence and the SRP guides the ribosome and its polypeptide to the ER membrane.

Step-by-step explanation:

The interaction between the ER signal sequence and the signal recognition particle (SRP) guides the ribosome and its polypeptide to the ER membrane. The SRP binds to the hydrophobic signal peptide on the growing polypeptide chain, which causes elongation to pause until the SRP-ribosome complex reaches the ER membrane. The ribosome-SRP complex then binds to an SRP receptor on the ER membrane, allowing translation elongation to resume and the polypeptide to be inserted into the ER.