Cell Biology 7 - Secretion

The manufacture and release of useful products from a cell.

Cells take small molecules from the bloodstream, transform them by intracellular mechanisms to complex functional molecules, and then release them into the cells' external environment.

The extracellular matrix: Collagens etc -structural support

Exocrine glands: Saliva, pancreatic juice, sweat, mucus etc.

Endocrine products: hormones

Plasma Proteins: albumens, blood clotting proteins, antibodies.


Lysosomal pathway and membrane proteins - use the secretory pathway, but not released from cell

Using Autoradiography.

Membrane of bound cisternae, with ribosomes on the outside

It is a network of interconnecting tubules, with no ribosome, connected to the RER.

Receives vesicle traffic from the ER - Proteins, membrane and membrane proteins.

Further Quality Control - Sends faulty materials back to the ER

Complex glycosilation reaction - Adds sugars to proteins

Sorting and packaging of contents

Targeting of products to final destination.

The cell has specific targeting systems which ensures that vessels go to the correct surface

It was discovered from viral behaviour.

They are released from the cell by exocytosis.

Concentration of contents

Targeting and transport to cell surface/lysosome

Membrane fusion and release of product

Delivery of new membrane lipids and proteins to cell surface.