When the function of the newly made polypeptide is to be secreted from the cell where it has been made, what must occur?
A) It must be translated by a ribosome that remains free of attachment to the ER.
B) Its signal sequence must target it to the ER, from which it goes to the Golgi.
C) It has a signal sequence that must be cleaved off before it can enter the ER.
D) It has a signal sequence that targets it to the cell's plasma membrane where it causes exocytosis.
E) Its signal sequence causes it to be encased in a vesicle as soon as it is translated.

Question

Quizplus · Accepted Answer

When a polypeptide is meant to be secreted, it must be translated by a ribosome that is attached to the endoplasmic reticulum (ER). The presence of a signal sequence on the polypeptide allows it to be targeted to the ER. Once in the ER, the polypeptide undergoes further modifications and is transported to the Golgi apparatus before being secreted out of the cell.

When the Function of the Newly Made Polypeptide Is to Be