Types of Endoplasmic Reticulum
The endoplasmic reticulum is like two factories in one. There's rough endoplasmic reticulum, or rough ER, and smooth endoplasmic reticulum, or smooth ER.
Rough ER
Rough ER gets its name because it's covered in ribosomes, which look like little bumps. Ribosomes are organelles that make proteins. When the ribosomes on the rough ER make enough protein, the protein is packed up by the endoplasmic reticulum and placed in sacs called vesicles. These vesicles can carry protein around the cell to structures that need it. The vesicles often carry the protein to the Golgi apparatus, where the protein can be used in different ways.
Rough ER works closely with the nucleus of the cell. Its surface connects with the membrane that surrounds the cell nucleus. This close relationship allows for the easy movement of molecules that help with protein production.
Smooth ER
Smooth ER doesn't have ribosomes, so its surface looks smooth. Since there are no protein-making ribosomes stuck to smooth ER, we don't see as much protein being made here. Instead, smooth ER helps make lipids, which are fats.
Some of these lipids help make the protective membrane that surrounds the cell. Steroids are a type of lipid made by the smooth ER. You might have heard of steroids before - professional athletes aren't allowed to use man-made steroids because they make muscles grow unusually big, giving the athlete an unfair advantage. It might surprise you to know that natural steroids are inside your body right now! Natural steroids help your body and are used to make certain hormones.
Smooth ER has another interesting job. It helps detoxify drugs and alcohol. Detoxification, which is the process of removing toxins, is an important function of your liver, so liver cells have a lot of smooth ER.
Lesson Summary
Endoplasmic reticulum is a collection of tubes that make, package, and transport proteins and fats. Rough endoplasmic reticulum has protein-making ribosomes on its surface, so it helps make and process proteins. Smooth endoplasmic reticulum helps make and process lipids and helps detoxify drugs and alcohol.
