Which is more important: smooth ER or rough ER?

Both are equally important. Cells need the smooth and rough ER to live.

The ER (endoplasmic reticulum) is classified into two types - smooth ER and rough ER. Although both have different functions, they work together to ensure the cells get what they need to live and function efficiently.

The smooth ER is associated with production and synthesis of lipids and steroid hormones, metabolism of carbohydrates, and storage and release of calcium ions. Cells specializing in the production of lipids and steroid hormones tend to have a larger amount of smooth ER.

The rough ER is associated with producing, folding, quality control, and dispatching proteins. Cells specializing in protein production and synthesis will have a large amount of rough ER.

Disruption in any of the processes can cause an imbalance in the ER’s homeostasis causing it to malfunction or stop working in extreme cases. When this happens, cells don’t get the crucial molecules they need to function and will die.