Page 46 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

1 - Endocytosis

A. Phagocytosis (cell eating)

.
Ingestion of solid particles by endocytosis

The cytoplasmic membrane folds inward and pinches off placing the

particle in a phagocytic vacuole. The phagocytic vacuole then fuses

with lysosomes forming a phagolysosome and the material is

degraded

B. Pinocytosis (cell drinking)

Ingestion of dissolved materials by endocytosis

The cytoplasmic membrane folds inward and pinches off placing small

droplets of fluid in a pinocytic vesicle. The liquid contents of the

vesicle is then slowly transferred to the cytosol

C. Receptor- Mediated Endocytosis

Movement of very specific molecules into the cell with
the use of vesicles coated with protein.

• When specific molecules bind to the receptors in coated pits, then

this stimulates the molecules to be engulfed into a coated vesicle.

2- Exocytosis

During exocytosis ,a cell releases waste products or specific secretion products

by the fusion of a vesicle with the cytoplasmic membrane

General Microbiology & Immunology (PM 401) theoretical handbook Page 35