The rough endoplasmic reticulum (RER) is is a series of flattened sacs connected to ribosomes. The Golgi Apparatus is an organelle composed of flattened stacked pouches known as <em>cisternae</em>.

In this case, the missing words indicate:

Specifically, this organelle is attached on the ROUGH ENDOPLASMIC RETICULUM (RER) which will help to modify and package the polypeptide product.

It puts it into a transport vesicle to be sent over to the GOLGI APPARATUS to add molecular tags and sort it, like a post office.

The RER is required for the production and secretion of different hormones and proteins.

The Golgi apparatus plays fundamental roles associated with the transport, modification, and packaging of proteins and lipids into vesicles, which are subsequently delivered to specific cellular destinations.