Question

As the messenger RNA is translated by the ribosome, the growing polypeptide chain is inserted into the membrane of the _____________ before being sent to its final destination. A) cell B) ribosome C) rough ER D) mitochondria

Answer 1

Endoplasmic reticulum 

Answer 2

Answer; The correct answer for the blank is-

C) rough ER ( rough endoplasmic reticulum).

mRNA is translated to form protein at ribosomes.

The proteins that are required to be secreted outside the cell are first transported to the endomembrane system ( which includes endoplasmic reticulum and golgi complex).

In the endoplasmic reticulum, post translational modification of protein takes place ( such as proper folding of protein). They are dispatched from the ER and move to golgi complex.

Finally, the vesicles ( containing proteins) exit from golgi, fuse with the cell membrane and are released outside the cell.

Example- When insulin is synthesized, it passes through the ER, where it is cut, folded and held in proper shape with the help of disulfide (-S-S-) bridges.

Thus, option C) is the right answer.