1How are specific macromolecules taken up in animal cells?
Macromolecules will bind to the transmembrane and receptor proteins inside clathring coated pits.
Enters the cell as receptor macromolecules complexes.
2What will a cell do when it needs cholesterol for membrane synthesis?
Plant transmembrane LDL receptors into its plasma membrane.
3What occurs if the uptake of cholesterol is inhibited or stopped?
Cholesterol will accumulate in the blood and can form plaque in the blood.
Cholesterol is transported in the blood in the form of LDL (low density lipoproteins).
4What are early endosomes synonymous with?
Vesicular tubular complexes
5Explain the process of how cholesterol is made:
- The LDL will bind to LDL receptors in the pits of the membrane. The pits form coated vesicles containing LDL.
- After shedding coat, the vesicles will deliver content to early endosomes.
- LDL is delivered via late endosome to a lysosome.
- The lysosome hydrolyzes LDL and frees cholesterol.
6Describe Early Endosomes
Sorting station for endocytosis
Acidic environment
Receptors will change conformations within endosomes and release their cargo/ligands. Cargo/ligands are hydrolyzed by lysosome.
7What is transcytosis?
When the receptors are recycled by retromer, the receptor can go to a different domain of the plasma membrane.
8Explain how endocytosed material moves from an early endosome to a late endosome:
- RAB5 to RAB7
- pH decreases
- Early endosomes travel along microtubules to interior of cell picking up vesicles and forming multivesicular bodies.
- Becomes late endosome
9How do late endosomes become lysosomes?
When they fuse with hydrolase transport vesicles from the Golgi.