Rough Endoplasmic Reticulum (Rough ER)

Definition

The rough endoplasmic reticulum (rough ER) is a network of interconnected tubules and flattened sacs within the cytoplasm of eukaryotic cells. It is called 'rough' due to the presence of ribosomes attached to its surface, which give it a granular appearance under a microscope. The rough ER plays a crucial role in the synthesis, folding, and modification of proteins destined for various cellular components or secretion.

5 Must Know Facts For Your Next Test

1. The rough ER is the site of synthesis for proteins destined for the secretory pathway, including proteins for the cell membrane, lysosomes, and extracellular matrix.
2. The ribosomes attached to the rough ER translate the genetic code into polypeptide chains, which are then transported into the lumen (interior) of the ER for further processing and modification.
3. The rough ER provides a specialized environment for the folding, assembly, and post-translational modification of newly synthesized proteins, such as the addition of carbohydrate groups (glycosylation).
4. The rough ER is continuous with the nuclear envelope, allowing for the direct transport of newly synthesized proteins from the nucleus to the ER lumen.
5. Disturbances in the function of the rough ER, such as improper protein folding or the accumulation of misfolded proteins, can lead to cellular stress and the activation of the unfolded protein response (UPR).

Review Questions

• Describe the structure and function of the rough endoplasmic reticulum (rough ER) in eukaryotic cells.
  • The rough endoplasmic reticulum (rough ER) is a network of interconnected tubules and flattened sacs within the cytoplasm of eukaryotic cells. It is called 'rough' due to the presence of ribosomes attached to its surface, which give it a granular appearance under a microscope. The primary function of the rough ER is the synthesis, folding, and modification of proteins destined for various cellular components or secretion. The ribosomes attached to the rough ER translate the genetic code into polypeptide chains, which are then transported into the lumen (interior) of the ER for further processing and modification, such as the addition of carbohydrate groups (glycosylation). The rough ER provides a specialized environment for the proper folding and assembly of these newly synthesized proteins, ensuring they are ready for their intended cellular functions.
• Explain the relationship between the rough ER and the secretory pathway in eukaryotic cells.
  • The rough endoplasmic reticulum (rough ER) plays a crucial role in the secretory pathway of eukaryotic cells. It is the site of synthesis for proteins destined for the secretory pathway, including proteins for the cell membrane, lysosomes, and extracellular matrix. The ribosomes attached to the rough ER translate the genetic code into polypeptide chains, which are then transported into the lumen (interior) of the ER for further processing and modification. The rough ER provides a specialized environment for the folding, assembly, and post-translational modification of these newly synthesized proteins, ensuring they are properly prepared for their intended cellular functions or secretion. The rough ER is continuous with the nuclear envelope, allowing for the direct transport of newly synthesized proteins from the nucleus to the ER lumen, facilitating their entry into the secretory pathway.
• Analyze the potential consequences of disruptions in the function of the rough endoplasmic reticulum (rough ER) and how this can impact cellular homeostasis.
  • Disturbances in the function of the rough endoplasmic reticulum (rough ER) can have significant consequences for cellular homeostasis. The rough ER plays a critical role in the synthesis, folding, and modification of proteins destined for various cellular components or secretion. If the proper functioning of the rough ER is disrupted, such as through improper protein folding or the accumulation of misfolded proteins, it can lead to cellular stress and the activation of the unfolded protein response (UPR). The UPR is a signaling pathway that attempts to restore cellular homeostasis by halting protein translation, increasing the production of chaperone proteins to aid in protein folding, and, if the stress persists, triggering apoptosis (programmed cell death). Failure to resolve the ER stress can have far-reaching consequences, including the impairment of essential cellular processes, the disruption of organelle function, and the potential development of various diseases, such as neurodegenerative disorders, metabolic diseases, and cancer. Therefore, maintaining the proper function of the rough ER is crucial for preserving cellular homeostasis and overall organismal health.

Related terms

Endoplasmic Reticulum (ER):

The endoplasmic reticulum is a vast network of interconnected tubules and flattened sacs that extend throughout the cytoplasm of eukaryotic cells, providing a platform for various cellular processes.

Smooth Endoplasmic Reticulum (Smooth ER): The smooth endoplasmic reticulum is a network of interconnected tubules and sacs within the cytoplasm of eukaryotic cells that lacks the ribosomes found on the rough ER, giving it a smooth appearance.

Ribosome:

Ribosomes are large, complex molecular machines found in the cytoplasm of cells that are responsible for the synthesis of proteins by translating the genetic code into functional polypeptide chains.