3.3 endomembrane system

what does the endomembrane system consist of

• endoplasmic reticulum (ER)

  • smooth one → makes lipids

  • rough one → makes membrane proteins

  • golgi → processing membrane proteins

• endosomes and lysosomes

  • uptake and processing → bulk transport

what benefits does an endomembrane give

• build and maintain the plasma membrane

• synthesize the lipids and get them to the right leaflet

• insert proteins with the right structure into the membrane

• add carbohydrates to the proteins / lipids and get them to the outside

• traffic large particles that have come in through bulk transport

• release things to the outside

what is the process of secreted and integral membrane proteins

1. ribosomes → make secreted and integral membrane proteins made directly at ER membrane → bound to rough ER

2. further processed in the golgi → sent to vesicles to the plasma membrane for export / incorporation via exocytosis

what is the process of endocytosis (bulk transport mechanism)

1. material taken in by endocytosis → trafficked to lysosome for degradation / recycling endosome for return to membrane

2. further processed in Golgi → sent to vesicles → to the plasma membrane for export / incorporation by exocytosis

what are some examples of endocytosis

• phagocytosis

• iron uptake

• signaling receptor recycling (controls sensitivity)

what is used to transport cargo through the endomembrane system

vesicles

• cargo is moved through the endomembrane system by vesicles that bud off and fuse with other membranes with active help from specialised protein machinery