1. Rough Endoplasmic reticulum – the structure
The basic structure consists of sheets of phospholipid membrane, which ribosome's are attached to.
Made up of a series of thin, intricate channels, and exists in the folds in the phospholipid membrane.
Many ribosome's are attached to endoplasmic reticulum. These are small dense organelles, about 20nm in diameter.
It also contains Cytosol, which is a solution containing enzymes.

2. Rough Endoplasmic reticulum – the functions
The narrow fluid-filled space between the membranes acts as a transport network which moves materials around the cell.
The folded membrane of ER creates a large surface area.
Ribosome's are the part of the RER which carry out protein synthesis. This is where RNA (produced by the nucleolus) binds to a ribosome, which uses the information encoded in the RNA to assemble amino acids in the correct order to produce the desired protein.
The protein produce in RER is exported from the cell for use elsewhere