Refer to the figure above and then answer the question that follows.
-What determines whether a protein will be produced on a "free ribosome or on one attached to the endoplasmic reticulum?
A) a chemical signal on the protein being produced
B) Every ribosome will migrate to the ER.
C) The mRNA of certain proteins moves directly to ribosomes already attached to the ER.
D) Microtubules attach randomly to ribosomes and move a fraction of them to the ER.

Question

Refer to the figure above and then answer the question that follows.
-What determines whether a protein will be produced on a "free ribosome or on one attached to the endoplasmic reticulum?
A) a chemical signal on the protein being produced 
B) Every ribosome will migrate to the ER. 
C) The mRNA of certain proteins moves directly to ribosomes already attached to the ER. 
D) Microtubules attach randomly to ribosomes and move a fraction of them to the ER.

Quizplus · Accepted Answer

The presence of a signal peptide (a chemical signal) on the protein being synthesized determines whether it will be directed to a ribosome on the endoplasmic reticulum (ER) for synthesis or will be synthesized on a free ribosome in the cytosol. This signal peptide guides the ribosome to the ER, where the protein is co-translationally translocated into the ER lumen if it is destined for secretion or insertion into a membrane.

Refer to the Figure Above and Then Answer the Question