6.2 Receptor-mediated Endocytosis Flashcards
Define ‘phagocytosis’
Internalisation of particulate matter
Name the process by which molecules leave a cell in a vesicle
Exocytosis
Define ‘pinocytosis’
Invagination of the plasma membrane to form a vesicle which allows the uptake of extracellular solutes.
Define ‘endocytosis’
The selective internalisation of molecules INTO a cell by binding to specific cell surface receptors.
Explain cholesterol uptake into a cell
LDLs containing cholesterol move into a cell via clathrin-coated pits which form spontaneously on a membrane surface. A clathrin-coated vesicle forms around the LDL and it moves into the cell.
How is a clathrin-coated vesicle uncoated?
ATP-dependent uncoating protein
Why do people suffer from hypercholesterolaemia?
Mutations have affected the LDL receptor. It may be faulty or not present at all.
What is a CURL (compartment of uncoupling of receptors and ligands)?
(Also known as an endosome)
It is a large membrane bound structure which fuses with other vesicles. It is more acidic than the rest of the cell because it has an ATP-dependent H+ pump.
State for LDL molecules:
How they enter a cell
What happens to the receptor
What happens to the ligand
They enter via a clathrin-coated pit
The receptor is recycled via the golgi
The ligand is degraded by hydrolases
State for ferrotransferrin molecules:
How they enter a cell
What happens to the receptor
What happens to the ligand
They enter via clathrin-coated pits
The receptor is recycled
The ligand is recycled
Fe3+ is released into the cytoplasm
State for IgA molecules:
How they enter a cell
What happens to the receptor
What happens to the ligand
Enter via clathrin-coated pits
The receptor is transported
The ligand is transported
State for insulin molecules:
What happens to the receptor
What happens to the ligand
The receptor is degraded
The ligand is degraded
How do membrane-enveloped viruses enter cells?
They take advantage of RME by binding to partially complementary cell receptors. They enter vis clathrin-coated pits. The virus RNA is then released into the cytoplasm.
