Short note on Golgi apparatus and endoplasmic reticulum.

Golgi apparatus

Golgi complex is smooth surfaced, closely packed intercommucating membrane bounded cisternae which are arranged in stack between the nucleus and the apical end of the cell.

• Packaging and shipping of proteins (secretory granules and transport vesicles)
• Important in the glycosylation, sulfating, phosphorylation.
• Membrane renewal
• Synthesis of Lysosomes







Endoplasmic reticulum

Endoplasmic reticulum

The endoplasmic reticulum or ER is an extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome studded (rough ER) and ribosome free (smooth ER) regions. Endoplasmic means "within the cytoplasm", and reticulum means "little net".

Types: two types

1. Rough (granular) endoplasmic reticulum
    
• Ribosomes make it rough ER
• Protein synthesis
• Ribosomes located on surface

2. Smooth endoplasmic reticulum
• Lipid synthesis
• No ribosomes
  
  

RER is present in cells specialized for protein secration, such as

·        pancreatic acinar cells

·        fibroblasts (collagen)

·        plasma cells

The ER modifies proteins (i.e. glycosylation), makes macromolecules, and transfers substances throughout the cell.