test 2, 14 vesicular trafficking

Question 1

What is the best environment for lysosomes?

Answer 1

• acidic with proteolytic cleavage sites

Question 2

What are lysosomes best used for?

Answer 2

intracellular digestion

Question 3

What maintains the acidic environment that lysosomes require to operate?

Answer 3

Vacuolar ATPase. Pumps H ions into the lysosomes environment

Question 4

What are the different stages of lysosome development?

Answer 4

1. early endosom
2. late endosome
3. endolysosome
4. lysosome

Question 5

What methods allow compounds to enter into a lysosome?

Answer 5

1. phagocytosis
2. endocytosis
3. autophagy
4. macropinocytosis

Question 6

What sorts hydrolases to lysosome form the TGN?

Answer 6

1. mannose-6-phosphate is required.

2. helps form a clathrin coated vesicle that is delivered to endosome and develops into lysosome

Question 7

What compound is used to add the M6P to the lysosomal hydrolase?

Answer 7

UDP-GlcNAc, which ultimately will fall off and leave M6P attached

Question 8

What is Hurler’s disease?

Answer 8

• mutation occurs in the enzyme that degrades glycosaminoglycan chain

Question 9

What is inclusion cell disease?

Answer 9

• lysosomal hydrolases are absent in multiple cell types, leading do substrate accumulation

Question 10

What enzyme is responsible for attaching M6P to lysosomal hydrolases?

Answer 10

• GlcNAc phosphotransferases. no phosphorylation means no signal that delivers vesicles to the lysosome.

Question 11

If GlcNAc is mutated and ineffective, where will compounds be transported if not sent to the lysosome?

Answer 11

• cell surface and secreted into the bloodstream

Question 12

What is endocytosis?

Answer 12

invagination of the PM that forms an endocytic vesicle of components from outside the cell. Use phagocytosis or pinocytosis

Question 13

What is receptor-mediated endocytosis?

Answer 13

1. selective concentration mechanism of uptake.

2. utilizesmolecules that bind to receptors and accumulate in clathrin-coated pits

Question 14

What is one example that utilizes receptor-mediated endocytosos? What happens if something in the system were to fail?

Answer 14

1. cholesterol

2. atherosclerosis

Question 15

What are the fates of proteins that have been endocytosed?

Answer 15

1. degradation via endolysome
2. transcytosis out of the cell
3. recycle of transport vesicles

Question 16

What is the process of phagocytosis?

Answer 16

1. performed by macrophages and neutrophils

2. fuse with lysosomes to degrade the ingested material

Question 17

Phagocytes use exocytosis in what scenario to do what?

Answer 17

1. secrete undigested material

Question 18

By what mechanism are phagocytes activated to perform phagocytosis?

Answer 18

1. Ab binds with Ag
2. interaction triggers pseudopod formation
3. pseudopod engulfs the Ag forming phagosome

Question 19

What controls and drives the pseudopod formation during phagocytosis?

Answer 19

1. actin polymerization and reogranization (structure rearrangement)
2. phosphoinositide and Rho GTPases signaling

Question 20

What is the first step in pinocytosis and what are the outcomes of the process?

Answer 20

1. clathrin coated pits start the process
2. continuous process in eukaryotes
3. ingest small bits of PM
4. traps extracellular fluid and solutes in the pits

Question 21

How are caveolae pits different than the clathrin coated pits?

Answer 21

1. enriched with cholesterol and glycosphingolipids and GPI anchored membranes
2. invagination occurs due to lipid content
3. require dynamin
4. unable to fuse with lysosome

Question 22

What is the process fo forming secretory vesicles?

Answer 22

1. proteins aggregate in the TGN
2. selected proteins packed into vesicles
3. secreted proteins also undergo proteolytic processing
4. require clathrin coats that fall away after formation of vesicle

Question 23

What proteins are required to form the binding components of exocytosis to occur?

Answer 23

1. synaptobrevin (v-SNARE)
2. syntaxin (t-SNARE)
3. SNAP25 (t-SNARE)

Question 24

What role does synaptotagmin have with exocytosis?

Answer 24

1. aids in fusion pore opening

Question 25

List the 6 steps in synaptic vesicle formation.

Answer 25

1. SV components must be delivered to PM 2. SV components endocytose to form new vesicles 3. SV components can migrate to endosome 4. SV buds from the endosome 5. NT loaded into the SV 6. NT is secreted when stimulated by action potential