IB BIOLOGY- Endocytosis and Exocytosis

Endocytosis and Exocytosis

1) Endocytosis- plasma membrane pulled inwards and pinched off.

2) proteins are synthesised by ribosomes and enter RER (rough endoplasmic reticulum)

3) Vesicles bud off from RER and carry proteins to golgi apparatus

4) Golgi apparatus modifies proteins and vesicles bud off

5) Exocytosis- vesicles fuse with plasma membrane and expelles content

Used to produce plant cell wall:

• Maintains cell shape
• Allows high pressure to build up in cell without bursting
• High pressue prevents excessive water uptake by osmosis
• Turgor pressure makes cell rigid

Used to produce glycoproteins in animals. This forms an extracellular matrix e.g.: around blood capillaries and alveoli in lungs.

• Support single layers of thin cells so they dont tear or perforate
• Cell to cell adhesion e.g: capillary walls adhere to alveolus wall