Question

Which of the following processes brings in large macromolecules and particles by the formation of a vesicle in the outer membrane?

Answer 1

The plasma membrane (outer membrane) is dynamic structure that functions to segregate the chemically distinct intracellular components from extracellular environment by regulating and coordinating the entry and exist of large and small molecules.

Macromolecules must be carried into the cell in membrane bound vesicles derived from invagination of plasma membrane by the process called endocytosis.

ENDOCYTOSIS

It is process of internalization of outside material inside the cell by fomation of invagination of the plasma membrane,followed by pinching off and release of free vesicles into the cytoplasm.

TYPES OF ENDOCYTOSIS

>Phagocytosis-In this large particles binds to specific plasma membrane receptors and by the formation of large endocytic vesicles called phagosomes.It normally occur in various specialized cells like macrophages and neutophils etc.It requires specific cell receptors for internalization of molecules.

>Pinocytosis- It involves ingestion of fluid and solutes by small vesicles.Before uptake the material is dissolved in extracellular fluid. Hence, pinocytosis occurs both selective and non selective i.e selective solutes have high specificity to the receptors present on cell surface.This receptor ligand (solute) complex will undergo endocytosis and incorporated into intracellular transport vesicles.