Exocytosis and endocytosis

Question 1

Describe the process of endocytosis.

Answer 1

1. endocytosis occurs when a membrane encloses a target particle;
2. fluidity of membrane permits movement of membrane;
3. membrane sinks inwardly/forms pit/invaginates to enclose particle;
4. a vesicle is formed;
5. membrane seals back on itself / edges fuse;
6. one membrane layer = two phospholipid layers enclose particle making vesicle;
7. inner phospholipid layer of (original) membrane becomes outer phospholipid layer of vesicle membrane;
8. outer phospholipid layer of (original) membrane becomes inner phospholipid layer of vesicle membrane;
9. vesicle breaks away from membrane/moves into cytoplasm;
10. changes in membrane shape require energy;