14.2

Flashcard 1

Q: What is gated transport? A: Movement of molecules between the cytosol and the nucleus through nuclear pore complexes.

Flashcard 2

Q: What is protein translocation? A: Transport of specific proteins across a membrane from the cytosol into a distinct space (e.g., ER, mitochondria).

Flashcard 3

Q: What is vesicular transport? A: Transport of proteins from one compartment to another using membrane-enclosed vesicles.

Flashcard 4

Q: What role do adaptor proteins play in vesicle budding? A: They select cargos to be packaged into a vesicle.

Flashcard 5

Q: How do coat proteins contribute to vesicle formation? A: They generate membrane curvature and encase the emerging vesicle.

Flashcard 6

Q: What is the function of membrane pinching proteins? A: They cut the budding neck to complete vesicle formation.

Flashcard 7

Q: What is the structure of clathrin? A: Clathrin is composed of multiple subunits that form a "triskeleton," creating pentagonal and hexagonal shapes.

Flashcard 8

Q: How do clathrin coats form? A: Clathrin coats introduce curvature into the membrane, leading to the formation of coated buds.

Flashcard 9

Q: What is the function of Rab proteins? A: Rab proteins guide transport vesicles to their target membranes by marking them with a "sender" address.

Flashcard 10

Q: How do Rab proteins interact with their effectors? A: Rab-GTP interacts with its effector on the target membrane, facilitating initial tethering.

Flashcard 11

Q: What is the role of dynamin in vesicle formation? A: Dynamin constricts and pinches off the vesicle from the plasma membrane.

Flashcard 12

Q: How does dynamin generate mechanical force? A: Dynamin hydrolyzes GTP, generating mechanical force to separate the vesicle from the membrane.

Flashcard 13

Q: What are SNARE proteins? A: SNARE proteins facilitate membrane fusion by bringing lipid bilayers close together.

Flashcard 14

Q: How do SNARE proteins overcome the energetically unfavorable process of membrane fusion? A: Specific SNARE pairing leads to vesicle fusion onto the target membrane.

Flashcard 15

Q: What is the role of monomeric GTPases in coat assembly? A: They control coat assembly, such as Sar1 on ER exit sites.

Flashcard 16

Q: How does Sar1 initiate membrane bending? A: Inactive Sar1-GDP binds to Sar1-GEF, causing Sar1 to release GDP and bind GTP, triggering membrane bending.

Flashcard 17

Q: What is the function of COPII adaptor coat proteins? A: They form the inner coat and select transmembrane proteins, causing membrane deformation.

Flashcard 18

Q: How do Rab proteins guide vesicles to target membranes? A: Rab-GTPs establish the first connection between the vesicle and target membranes.

Flashcard 19

Q: What is the role of Rab effector proteins? A: They interact with active Rab proteins to facilitate initial tethering.

Flashcard 20

Q: How do SNARE proteins dock vesicles to target membranes? A: SNARE proteins on the vesicle and target membrane pair, docking the vesicle and catalyzing fusion.

Flashcard 21

Q: What happens to proteins produced in the ER? A: They can be transported to other components of the endomembrane system, such as the Golgi complex, or remain in place as ER resident proteins.

Flashcard 22

Q: How is the acidification of organelle lumen achieved? A: By active transport (pumping) of H+ into the lumen.

Flashcard 23

Q: What is the role of the Golgi complex? A: In the Golgi, glycoproteins, membrane proteins, secreted proteins, and membrane lipids from the ER undergo further processing, sorting, and packaging for transport.

Flashcard 24

Q: What is the function of the trans-Golgi network (TGN)? A: Proteins and lipids leave the Golgi in transport vesicles that continuously bud from the tips of the TGN.

Flashcard 25

Q: What are the two models depicting the flow of lipids and proteins through the Golgi complex? A: The stationary cisternae model and the cisternal maturation model.

Flashcard 26

Q: What is the KDEL sequence? A: A retention signal (Lys-Asp-Glu-Leu) for ER-resident proteins that ensures they are retrieved from the Golgi back to the ER.

Flashcard 27

Q: What are the three post-Golgi transport pathways? A: Lysosomal sorting (via endosomes), plasma membrane (constitutive secretion), and secretory vesicles (regulated secretion).

Flashcard 28

Q: What is the principal function of lysosomes? A: Intracellular digestion, containing various hydrolases that are active at low pH.

Flashcard 29

Q: How are lysosomal hydrolases sorted in the trans-Golgi network? A: By mannose 6-phosphate (M6P) receptors that bind M6P-tagged hydrolases and direct them to lysosomes.

Flashcard 30

Q: What is autophagy? A: A process where unwanted proteins and organelles are degraded by being sequestered in autophagosomes that fuse with lysosomes.

Flashcard 31

Q: What is regulated exocytosis? A: The process where secretory vesicles are stored near the synaptic release site and released upon receiving a signal.

Flashcard 32

Q: What triggers GLUT4 translocation to the plasma membrane? A: Insulin signaling, which causes the rapid insertion of glucose transporters into the plasma membrane.

Flashcard 33

Q: What is synaptic vesicle exocytosis? A: The release of neurotransmitters from synaptic vesicles upon neuronal depolarization.

Flashcard 34

Q: What are the four types of endocytosis? A: Pinocytosis, macropinocytosis, receptor-mediated endocytosis, and phagocytosis.

Flashcard 35

Q: What is phagocytosis? A: The ingestion of large particles, often referred to as "cellular eating."

Flashcard 36

Q: What are clathrin-coated pits? A: Specialized regions of the plasma membrane where clathrin-mediated endocytosis occurs.

Flashcard 37

Q: What are caveolae? A: Small invaginations in the plasma membrane formed by caveolin, involved in endocytosis.

Flashcard 38

Q: What is macropinocytosis? A: The non-specific uptake of extracellular fluid in large vacuoles called macropinosomes.

Flashcard 39

Q: What is receptor-mediated endocytosis? A: The selective uptake of extracellular macromolecules via receptors on the cell surface.

Flashcard 40

Q: What is an example of receptor-mediated endocytosis? A: The uptake of low-density lipoprotein (LDL) particles by LDL receptors.

Flashcard 41

Q: How does LDL uptake occur? A: LDL binds to LDL receptors, is internalized, separated from the receptor in endosomes, and the receptor is recycled back to the plasma membrane.

Flashcard 42

Q: What is the role of the pHluorin GFP variant? A: It exhibits pH-sensitive fluorescence and can be used to measure pH in organelles.

Flashcard 43

Q: What is the function of the Golgi's medial cisternae? A: Much of the processing of proteins occurs in the medial cisternae between the TGN and CGN.

Flashcard 44

Q: What is the significance of the Golgi's biochemical polarity? A: Each compartment contains specific proteins unique to each portion of the network, maintaining its function and identity.

Flashcard 45

Q: How do ER-resident proteins maintain their location? A: Through retention and retrieval signals, such as the KDEL sequence, ensuring they are returned to the ER from the Golgi.

Flashcard 46

Q: What is the role of mannose 6-phosphate (M6P) in lysosomal sorting? A: M6P tags lysosomal hydrolases, directing them to lysosomes via M6P receptors in the trans-Golgi network.

Flashcard 47

Q: What is the process of autophagy? A: A signaling pathway initiates nucleation, forming an autophagosome that fuses with lysosomes to digest its contents.

Flashcard 48

Q: How does regulated exocytosis occur in synaptic vesicles? A: Synaptic vesicles dock at the membrane, SNARE proteins partially assemble, and upon Ca2+ entry, fusion occurs, releasing neurotransmitters.

Flashcard 49

Q: What is the role of complexin in synaptic vesicle exocytosis? A: Complexin prevents premature fusion of the SNARE bundle until Ca2+ binds to synaptotagmin, triggering fusion.

Flashcard 50

Q: What is the function of recycling endosomes? A: They serve as intracellular storage sites for specialized plasma membrane proteins that can be mobilized when needed.

Flashcard 51

Q: What is pinocytosis? A: The uptake of plasma membrane along with extracellular fluid (cellular drinking).

Flashcard 52

Q: What is macropinocytosis? A: The non-specific uptake of extracellular fluid in large vacuoles called macropinosomes.

Flashcard 53

Q: What is receptor-mediated endocytosis? A: The selective uptake of extracellular macromolecules via receptors on the cell surface.

Flashcard 54

Q: What is phagocytosis? A: The ingestion of large particles, often referred to as "cellular eating."

Flashcard 55

Q: What is the role of clathrin-coated pits in endocytosis? A: Specialized regions of the plasma membrane where clathrin-mediated endocytosis occurs.

Flashcard 56

Q: What are caveolae? A: Small invaginations in the plasma membrane formed by caveolin, involved in endocytosis.

Flashcard 57

Q: What is an example of receptor-mediated endocytosis? A: The uptake of low-density lipoprotein (LDL) particles by LDL receptors.

Flashcard 58

Q: How does LDL uptake occur? A: LDL binds to LDL receptors, is internalized, separated from the receptor in endosomes, and the receptor is recycled back to the plasma membrane.

Flashcard 59

Q: What is the role of the pHluorin GFP variant? A: It exhibits pH-sensitive fluorescence and can be used to measure pH in organelles.

Flashcard 60

Q: What is the function of the Golgi's medial cisternae? A: Much of the processing of proteins occurs in the medial cisternae between the TGN and CGN.

Flashcard 61

Q: What is the significance of the Golgi's biochemical polarity? A: Each compartment contains specific proteins unique to each portion of the network, maintaining its function and identity.

Flashcard 62

Q: How do ER-resident proteins maintain their location? A: Through retention and retrieval signals, such as the KDEL sequence, ensuring they are returned to the ER from the Golgi.

Flashcard 63

Q: What is the role of mannose 6-phosphate (M6P) in lysosomal sorting? A: M6P tags lysosomal hydrolases, directing them to lysosomes via M6P receptors in the trans-Golgi network.