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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Imagine a chain of pearls with each of the pearls being a different color. Different combinations of colors result in different types of chains. This is precisely how amino acid chain sequence determines the type of protein it will become. It is then folded into its fully functional structure.
Once the protein has been assembled, it then undergoes another key factory function: quality control. It is checked for flaws and if found faulty, kicked out to the cytoplasm to be broken back down into individual amino acids. A flawed protein could be deformed or otherwise fail to function properly, causing defects in the cell or organism. If found intact, the protein is exported from the ER and sent off to other parts of the cell for use.
The rough ER is an organelle found in eukaryotic cells and is devoted to protein manufacturing and export. It consists of many folded layers of membrane, across which a high volume of proteins can be produced. The 'rough' description pertains to the millions of tiny ribosomes, which are embedded on the exterior of the ER and function to translate DNA code into an amino acid chain. In the ER membranes, the chain is folded into a protein, checked for quality, and then exported into the cell cytoplasm for various uses. This part of the cell works much like a factory, with the critical job of making sure the cell, and entire organism, has all the necessary proteins to function optimally.
In this activity, students will be combining their knowledge of the rough ER from the lesson and learning how to create a resume. Here, students will create a resume for the rough ER that depicts as a personified organelle looking for a job in a new cell. This creative project will help students work on resume writing skills and interact with the material in a new way. For example, students might write in the essential skills section of the resume that the rough ER has experience "building and modifying proteins that are destined for secretion or the endomembrane system." They might also include personal details such as "has a close working relationship with ribosomes and the nucleus." Students can be as creative as they want!
Now that you're familiar with the rough ER, we're going to put our creative thinking hats on. In this activity, you'll be building a resume for the rough ER. You should keep your resume to one page in length and be sure to include appropriate major sections, such as past work experience, important skills, or education. Make sure to include all of the necessary information from the lesson and look over the criteria for success below to make sure your resume has everything it needs.
Criteria for Success
Resume is one page in length
Resume is professionally designed
Resume includes at least three major sections, such as work experience, education, or skills
Resume includes scientifically accurate information about the rough ER
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