Endoplasmic Reticulum

Endoplasmic Reticulum

  • Electron microscopic studies of eukaryotic cells reveal the presence of a network of tiny tubular structures scattered in the cytoplasm known as the endoplasmic reticulum (ER).  
  • This network divides the intracellular space into two distinct compartments: the luminal space (inside the ER) and the extraluminal space (cytoplasm). 
  • Ribosome Attachment:

- The ER often displays ribosomes attached to its outer surface.

- When ribosomes are present, it is referred to as rough endoplasmic reticulum (RER).

- In the absence of ribosomes, it appears smooth and is called smooth endoplasmic reticulum (SER). 

  • RER Function: 

- RER is frequently observed in cells that are actively involved in protein synthesis and secretion.

- It forms an extensive and continuous connection with the outer membrane of the nucleus. 

  • SER Function:

- Smooth endoplasmic reticulum (SER) serves as the major site for lipid synthesis.

- In animal cells, SER is responsible for the synthesis of lipid-like steroidal hormones, which are essential for various physiological processes.