The Endoplasmic Reticulum is found in both plant and animal cells. It's a network of membranes that extends throughout the cytoplasm of the cell.

Here's a breakdown of its key roles:

* Protein Synthesis and Folding: The ER is involved in the synthesis and modification of proteins destined for secretion or for use in other cellular compartments.

* Lipid Synthesis: It is also responsible for the synthesis of lipids and steroids.

* Calcium Storage: The ER can store calcium ions, which play a role in various cellular processes.

* Detoxification: In some cells, the ER helps detoxify harmful substances.

Key Difference:

While both plant and animal cells have an ER, there are differences in its structure and function between the two. Plant cells often have a more extensive ER network, and they may have specialized regions of the ER involved in cell wall formation.