Rough ER: Definition, Function & Structure

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  • 0:30 What Is Rough ER?
  • 0:57 Rough ER Structure
  • 1:31 The Function of Rough ER
  • 2:41 Lesson Summary
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Lesson Transcript
Instructor: Meredith Mikell
In this lesson, we will look at the busy workings of the rough ER. Here we will establish its definition, examine its function, and observe its structure. At the end, you can test your knowledge with a short quiz.

What Is Rough ER?

Just like your body is comprised of many different organs, which work together in organ systems to ensure healthy function, individual cells have many different organelles that work in similar ways. One of the most key roles of these organelles has to do with proteins. It is proteins that affect pretty much all functions, metabolizing, and physiological features of cells, so it is crucial that proteins be constructed properly.

That is where the rough endoplasmic reticulum (ER) comes in. This organelle is the site of protein production, folding, quality checking, and export to other parts of the cell. Some of these proteins end up embedded in cell membranes to assist in metabolism, some become enzymes, and some become support structures. The ER as a whole can be compared to a factory: manufacturing, quality control, and shipping!

Rough ER Structure

Like other cell organelles, the ER is comprised of many folded layers of membrane. This ensures a high surface area for protein and lipid production, kind of like having a very large workbench. Cells have two types of ER: rough and smooth.

The rough ER is named so because its outside is covered with millions of ribosomes, tiny organelles responsible for protein assembly, also known as translation. Ribosomes are also found free roaming in the cytosol and near the outside of the nucleus. Smooth ER lacks ribosomes and is devoted to the manufacturing of lipids.

The Function of Rough ER

If the ER is a factory, then the cell nucleus is the corporate headquarters, sending the factory blueprints of items to be constructed. In cells, these blueprints, DNA code, are meant to construct different types of proteins. When the ribosomes on the outside of the rough ER receive the blueprints, they then begin the process of translating the code into the specific amino acid sequence that will result in a specific type of protein.

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