Endocytosis and Exocytosis

Exocytosis

process of material leaving the cell

Endocytosis

process of the cell engulfing materials

Types of endocytosis

penocytosis (liquids)

phagosytosis (solids)

receptor mediated

Steps of Exocytosis

1) Substance leaves golgi and enters a vesicle

a. Vesicle has v-snares on it and coat proteins that surround it that pinch the vesicle off golgi

b. Substance has a tag protein

2) Vesicle with substance walks on microtubules (kinesin) to bring it to cell membrane

3) On cell membrane there are t-snares, which help attach the vesicle to the membrane and release the substance outside of the cell

Steps of Endocytosis

1) Take substance (such as collagen) and it approaches the plasma membrane

2) Plasma membrane starts engulfing substance with the code proteins in the cytoplasm.

3) Brings in the substance with a vesicle and a primary lisosome attached

Steps for Receptor Mediated Cytosis

1) Cholesterol in the ECM approaches the plasma membrane.

a. ECM part of the plasma membrane contains low density lipoproteins.

b. LDL receptors are in the plasma membrane and are attached to the clatherin coated pit.

2) Cholesterol and LDL receptors bind

3) Clatherin pinches off vesicle, gets recycled.

4) Vesicle splits into 2, one with cholesterol and LDL and the other with LDL receptors.

a. LDL receptors get recycled.

5. Primary lysosome carries cholesterol and LDL.