Solution:
The endoplasmic reticulum is a network of interconnected membranes that branch throughout the cytoplasm of a eukaryotic cell, forming flattened tubes and sacs (ER). Parts of the ER contain ribosomes, which are temporarily attached to the outer faces of its flattened sacs.
The rough endoplasmic reticulum (ER):
The region of the endoplasmic reticulum that contains ribosomes is called the rough endoplasmic reticulum or RER.
STRUCTURE: By electron microscopy, these regions are seen flattened and with granules (the ribosomes)
FUNCTION:
This region has two functions:
1. Secrete certain newly synthesized proteins out of the cytoplasm and transport them to other places in the cell.
2. When proteins are inside the RER, they are chemically modified in order to alter their function and final destination.
The Smooth endoplasmic reticulum (SER):
STRUCTURE:
The smooth endoplasmic reticulum is more tubular in build and lacks ribosomes.
FUNCTIONS:
1. Chemically modifies small molecules taken up by the cell. This is especially true for drugs and pesticides.
2. In animal cells, the smooth endoplasmic reticulum is the site where glycogen hydrolysis occurs in animal cells.
3. It is the site for lipid and steroid synthesis.
4. Within the lumen of the smooth endoplasmic reticulum, proteins that have been synthesized in the ER are chemically modified