The Endomembrane System

Lecture 12

Endomembrane System

regulates protein traffic and essential metabolic functions

Smooth Endoplasmic Reticulum (composition & functions)

lacks ribosomes

Functions:

• synthesizes lipids

• detoxifies

• stores calcium ions

Rough Endoplasmic Reticulum (composition & functions)

studded with ribosomes

Functions:

• synthesizes glycoproteins

• membrane production

Golgi Apparatus (composition & functions)

composed of cisternae

Functions:

• modifies ER products

• manufactures macromolecules

• sorts/packages materials into vesicles

• cis face = receiving, trans face = shipping

Lysosomes (composition & functions)

contains hydrolytic enzymes

Functions:

• digests biomolecules

• phagocytosis: engulfs another cell

• autophagy: breaks down cell & recycles it

Food Vacuoles

engulfs and breaks down food particles (protists)

Contractile Vacuoles

expels water (protists)

Central Vacuoles

stores water and organic compounds (plants)

Vesicles

small vacuoles in animal cells

Peroxisomes

in liver and kidney cells

Functions:

• lipid metabolism & detoxification

• byproduct of hydrogen peroxide → converted into water