Lecture 5: Endomembrane System and Bulk Transport Processes Flashcards
Define the endomembrane system.
The endomembrane system is the system in which organelles work together to modify packages and transport material around the cell via vesicles. Each organelle has a different function in this process.
What is the role of rough ER?
Synthesize proteins because it is studded with ribosomes.
Where do secreted and membrane bound proteins enter in the rER?
The lumen, interior of the rER.
Where does the synthesis of cytoplasmic proteins occur?
Free ribosomes, not the rER.
What is the role of smooth ER?
Synthesis of lipids such as phospholipid and hormones. Metabolism of carbohydrates. Detoxification of drugs. Storage of calcium ions.
Why is the Golgi complex considered polar?
Because it is an asymmetrical shape with a trans and cis face.
What is the function of the Golgi complex?
To receive material, sort it, modify it if needed and send it out. Material comes in at the cis face and leaves at the trans.
What does the Golgi complex send materials out in?
Vesicles
What is glycolysation and where does it occur?
It occurs within the Golgi complex. Glycolysation is where a carbohydrate is added to a protein to make a proteoglycan / glycoprotein.
How does the Golgi complex sort materials.
Adds a molecular marker to direct proteins to the correct vesicle.
What is the function of a glycoprotein?
To enable a cell to be recognized by other cells and proteins.
How do vesicles which exit at the trans face of the Golgi face know where to go?
They are tagged with a molecular marker usually a glycoprotein which tells it where to go.
What is a lysosome?
Membranous sac of hydrolytic enzymes that can digest macromolecules.
Do lysosomes have a higher pH or lower pH than the cytosol?
Lower pH, more acidic.
What is exocytosis? What types are there?
Transport of material out of the cell. 2 types constitutive and regulated. The difference between the two is that regulated is much more controlled and less frequent as it releases neurotransmitters and hormones while constitutive releases extracellular matrix proteins.
