1030-Endocytosis and intracellular vesicle trafficking

Question 1

Endocytosis definition

Answer 1

the process of uptake of outside material via invagination of the plasma membrane which then pinches to form an intracellular vesicle

Question 2

3 reasons why the cells need endocytosis

Answer 2

the lipid bilayer is poorly permeable to ions and macromolecules, small and large molecules can enter through protein carriers and channels, macromolecules cannot enter through membrane bound carriers so they enter through endocytosis.

Question 3

Phagosome

Answer 3

a vesicle formed around a particle and engulfed by a phagocyte.

Question 4

Phagocytosis mechanism :

Answer 4

1. receptors which bind to bacteria become activated 2. F-actin polymerisation
2. Plasma membrane moves around the particle and the phagosome is sealed off.
3. F-actin dissociates
   Phagosome is then transported into the cell, phagosome fuses with lysosome to form phagolysosome then the content inside the phagosome is then degraded.

Question 5

Clathrin

Answer 5

a protein which plays a major role in the formation of coated vesicles.