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.
