Zaidi: Trafficking 2

Question 1

Antibody interaction in phagocytosis

Answer 1

Antibodies bind to microbe, Fc chain recognized by Fc receptor on macrophage/neutrophil
Binding triggers formation of pseudopod which engulfs particle and forms phagosome

Question 2

Regulated secretory pathway

Answer 2

Triggered by signals

Question 3

Blockage of cholesterol uptake pathway results in

Answer 3

Atherosclerosis

Question 4

Constitutive secretory pathway

Answer 4

Operates continuously

Question 5

Hurlers disease

Answer 5

Mutation in the enzyme required to break down glycosaminoglycan chains

Question 6

GlcNAc phosphotransferase

Answer 6

Transfers GlcNAc-Pi to mannose to create GlcNAc-M6P

GlcNAc is then removed and you have M6P

Question 7

Phagocytes include

Answer 7

WBCs such as macrophages and neutrophils

Question 8

Storage of receptor proteins in recycling endosomes

Answer 8

Receptor proteins such as glucose transporters can be stored in endosomes.
Cell recieves signal that it needs more glucose when insulin binds insulin receptor
More glucose transporters are then transported to membrane from endosomes

Question 9

Proteins destined for secretion are packaged where and involves what

Answer 9

Into secretory vesicles in the TGN

Involves selective aggregation/clumping of proteins

Question 10

Lysosomal storage disease

Answer 10

Genetic defects in lysosomal hydrolases

Accumulation of undigested material in lysosomes

Question 11

Vesicle coat involved in pinocytosis

Answer 11

Clathrin coated pits

Question 12

Proteins are concentrated into vesicle by

Answer 12

Retrieval of other proteins that go back to TGN and ER

Question 13

Pseudopod formation driven by and controlled by

Answer 13

Driven by localized actin polymerization and reorganization

Controlled by Rho GTPases and PI signaling

Question 14

LDL receptors have binding site for

Answer 14

Clathrin, to ensure the vesicle forms around the LDL receptors

Question 15

Membrane protein/hydrolases transport to lysosomes

Answer 15

Co-translationally transported into RER and then transported via golgi complex to TGN
TGN buds off into endosomes which develop into lysosomes

Question 16

Phagocytosis

Answer 16

Large particles ingested by phagosomes

Question 17

What happens to undigested material

Answer 17

It is secreted through exocytosis

Question 18

Lysosomal hydrolases have what sorting signal

Answer 18

Mannose-6-Phosphate is attached to them in the Cis golgi network
M6P receptors in TGN recognize the sugar

Question 19

Vacuolar ATPase

Answer 19

Pumps H+ into lysosomes to maintain acidid pH and drive transport of small metabolites

Question 20

Caveolae

Answer 20

Flask-shaped invaginations in PM, enriched in cholesterol and glycosphingolipids
Major structural protein is Caveolin

Question 21

TGN promotes

Answer 21

Proteolytic processing of the secretory proteins- activation mechanism

Question 22

Inclusion cell disease

Answer 22

All of the lysosomal hydrolases are missing in many cell types. Undigested substrates accumulate as “inclusions”

Question 23

Defective or missing GlcNAc phosphotransferase

Answer 23

Lysosomal hydrolases with mannose are never phosphorylated to create M6P.
Therefore, hydrolases do not get delivered to lysosomes, they are carried to cell surface and secreted

Question 24

Caveolae invaginate into membrane by virtue of, they pinch off from PM by

Answer 24

Lipid composition, NOT the clathrin coat
Pinch of PM by dynamin-form caveosome
These DO NOT connect with lysosomes

Question 25

Exocytosis route

Answer 25

Transport vesicles move from TGN to PM

Question 26

What happens to LDL receptors after they successfully bring LDL into endosomes

Answer 26

They are recycled back to the plasma membrane

Question 27

What type of vesicles bud off from TGN to create endosomes

Answer 27

Clathrin-coated vesicles

Question 28

Receptor-mediated endocytosis

Answer 28

Imports select macromolecules from outside cell
They bind receptors on membrane and accumulate in clathrin coated pits
Example of this mechanism is cholesterol uptake

Question 29

Endocytosis

Answer 29

Uptake of macromolecules from exterior across plasma membrane

Question 30

Pinocytosis

Answer 30

Small particles ingested by pinocytic vesicles

Question 31

Lysosomes are derived from and contain

Answer 31

Late endosomes

Contain hydrolytic enzymes