Question

why the rough endoplasmic reticulum appears rough

Answer 1

Rough ER is found throughout the cell but the density is higher near the nucleus and the Golgi apparatus. Ribosomes on the rough endoplasmic reticulum are called 'membrane bound' and are responsible for the assembly of many proteins. This process is called translation.

Answer 2

the rough endoplasmic reticulum appears rough because on the surface of rer some ribosomes present which make them rough