Lysosome, peroxysome, ER, golgi, endo- exocytosis

Intracellular systems that take part in vesicular transport

Golgi apparatus

RER & SER

Lysosomes

Endosomes

Secretory vesicles

SER Functions

Phospholipid, cholesterol, ceramide synthesis.

Regulation of Ca2+ levels in cells

Glucose metabolism

RER functions

Synthesis, modification, sorting, and transport of lysosome integral membrane proteins.

Correct spatial structure of proteins is developed in the cavity of RER (by chaperons)

‘Quality control’ for proteins with inadequate spatial structure.

Golgi structure

Heterogenous membrane system

Collection of fused, flattened membrane enclosed discs known as cisternae

Dynamic structure

Cis and trans compartment

Cis-golgi network function

Collecting and sorting proteins from ER

Sorting and separation of lysosomal enzymes, adding M-6-P label to protein.

Adding retention signals to soluble proteins and direct them back in vesicles to ER (retrograde transport).

Trans-golgi network

Endosomal-lysosomal system

Plasma membrane

Secretory vesicles

Endosomal-lysosomal systems

Regulated secretion (digestive proteases destined for lysosome)

Plasma membrane

Constitutive secretion, exocytosis (antibody release)

Secretory vesicles

Regulatory secretion, exocytosis (neurotransmitter release)

Mannose 6 phosphate steps

Addition of phosphate

Phosphate binds to M6P receptor

Receptor-dependent transport in transport vesicle

Phosphate transported to late endosome

Dissociation of vesicle at acidic pH

Removal of phosphate

Receptors recycled

Types of endocytosis

Phagocytosis

Pinocytosis

Receptor-mediated endocytosis

Caveolae

Phagocytosis

Immune process, removal of microorganisms

Autophagy

Cell removes unnecessary or dysfunctional components of own cells, controlling the number of cellular organelles, removing ageing organelles.

Peroxisome function

Oxidative breakdown of fatty acids, purines, and amino acids.

Eliminates H2O2 from cells

Removes toxic molecules from liver and kidney

Synthesizes cholesterol, bile, unsaturated fatty acids.

Proteasome function

non-lysosomal pathway of protein breakdown

Responsible for the breakdown of damaged or not properly folded proteins and unassembled proteins.