L4 Endomembrane system and bulk transport

endomembrane system

A network of membranes within a cell that divides it into functional and structural compartments.

main components of the endomembrane system

ER, Golgi apparatus, lysosomes, vesicles, and the plasma membrane.

function of the endoplasmic reticulum (ER)

Responsible for the synthesis of proteins and lipids, is divided into rough ER and smooth ER.

role of the Golgi apparatus

Modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

function of lysosomes

Organelles that contain digestive enzymes to break down waste materials and cellular debris.

phagocytosis

A type of endocytosis (Bulk transport into the cell) in which a cell engulfs large particles or microorganisms. (Cell eating)

pinocytosis

A type of endocytosis where the cell takes in liquid along with small molecules. (Cell drinking)

receptor-mediated endocytosis

A specialised form of Pinocytosis, where receptor proteins are used to take up bulk quantities of a specific substance.

exocytosis

A process by which a cell exports substances in vesicles that fuse with the plasma membrane. Bulk transport out of the cell

two types of exocytosis

constitutive exocytosis = occurs continuously

regulated exocytosis = controlled and occurs in response to specific signals.

Vesicle

A small membrane-bound sac within a cell that transports and stores substances.

Lysosome

Organelles that contain digestive enzymes to break down waste materials and cellular debris.

Difference between sER and rER

The smooth ER (sER) lacks ribosomes and is involved in lipid synthesis and detoxification, while the rough ER (rER) has ribosomes on its surface and is primarily involved in protein synthesis.

function of the endomembrane system

Facilitates synthesis, modification, transport, and breakdown of proteins and lipids, as well as the cellular intake and export of materials.