MCB 2050 Exam Questions and Answers
100% Correct
tethering factors Correct Answ_highly elongated (fiber-like, rod-shaped) proteins or
components of large multi-protein complexes
v-SNAREs Correct Answ_found on transport vesicle membranes
t-SNAREs Correct Answ_found on target acceptor membranes
retrograde transport of escaped ER proteins Correct Answ_integral transmembrane protein
binds to KDEL sequence on escaped ER protein and cytoplasmic-facing domain of KDEL
receptor binds to COPI components
COPI vesicle returns *soluble ER protein*-KDEL receptor complex back to the ER
at the ER, KDEL receptor releases the protein and returns to the CGN via COPII
*ER membrane proteins* possess a cytoplasmic-facing, C-terminal KKxx (dilysine) sequence,
which is also recognized by COPI and KDEL receptor and transported back to the ER
KDEL sequence Correct Answ_ER retrieval signal
,Golgi complex Correct Answ_complex of flattened membrane-bound cisternae (sacs)
w/dilated edges and numerous associated tubules and vesicles
1 per mammalian cell
multiple in plant and yeast cells
organization of stack is mediated by Golgi matrix, also links Golgi to cytoskeleton
GRASPs Correct Answ_serve as tethering proteins to link different Golgi subcompartments
together
- RNAi of GRASPs results in disassembly of the Golgi complex
CGN Correct Answ_cisGolgi network
interconnected network of tubules and vesicles adjacent to ERES and ERGIC
ERGIC Correct Answ_initial destination of COPII vesicles from ERES
vesicles can fuse to form larger vesicles and interconnected tubules
vesicular-tubular carriers move towards CGN via cytoskeleton
srves as a sorign station
,Golgi cisternae Correct Answ_3+ large, flattened cisternae
divided into cis, medial, and trans
TGN Correct Answ_transGolgi network
serves as a sorting station
involved in forward transport of materials from Golgi to other compartments
site of secretory vesicle/granule assembly and COPI assembly
glycosylation in the Golgi Correct Answ_cis, medial, and trans cisternae possess unique
glycosyltransferase enzymes that sequentially modify the glycoprotein's core oligosaccharide in
specific ways
other modifications serve as targeting signal for proteins destined for lysosome
ex. alpha-mannosidase I, which removes 3 mannose sugars from the core oligosaccharide
M6P Correct Answ_2 mannose sugars in the core oligosaccharide that were phosphorylated
serves as signal patch for lysosomal targeting via secretory pathways
, what do proteins w/out an M6P do? Correct Answ_packaged into other TGN transport
vesicles or granules destined for pm and extracellular space via the secretory pathway
cisternal progression/maturation model Correct Answ_composition of each subcompartment
changes while moving from cis to trans through stack
CGN matures into cis cisternae, which matures into medial, which matures into trans, etc.
Golgi complex persists overall bc transport vesicles continually move resident Golgi proteins
back to the proper subcompartment and COPII transporting vesicles from ERES and VTCs via
ERGIC that fuse together to form a new CGN
TGN eventually disperses into various vesicles that traffic to endosomes/lysosomes or to pm
lysosome Correct Answ_aka vacuole in plants
digestive organelle, degrades all types of macromolecules and play key role in degradation of
cellular organelles/components (autophagy)
only active at pH 4.6 (maintained by H+ pumps)
resident lysosomal membrane proteins are protected by their CHO groups
products of degradation are transported into cytoplasm and reused by various biosynthetic
pathways
100% Correct
tethering factors Correct Answ_highly elongated (fiber-like, rod-shaped) proteins or
components of large multi-protein complexes
v-SNAREs Correct Answ_found on transport vesicle membranes
t-SNAREs Correct Answ_found on target acceptor membranes
retrograde transport of escaped ER proteins Correct Answ_integral transmembrane protein
binds to KDEL sequence on escaped ER protein and cytoplasmic-facing domain of KDEL
receptor binds to COPI components
COPI vesicle returns *soluble ER protein*-KDEL receptor complex back to the ER
at the ER, KDEL receptor releases the protein and returns to the CGN via COPII
*ER membrane proteins* possess a cytoplasmic-facing, C-terminal KKxx (dilysine) sequence,
which is also recognized by COPI and KDEL receptor and transported back to the ER
KDEL sequence Correct Answ_ER retrieval signal
,Golgi complex Correct Answ_complex of flattened membrane-bound cisternae (sacs)
w/dilated edges and numerous associated tubules and vesicles
1 per mammalian cell
multiple in plant and yeast cells
organization of stack is mediated by Golgi matrix, also links Golgi to cytoskeleton
GRASPs Correct Answ_serve as tethering proteins to link different Golgi subcompartments
together
- RNAi of GRASPs results in disassembly of the Golgi complex
CGN Correct Answ_cisGolgi network
interconnected network of tubules and vesicles adjacent to ERES and ERGIC
ERGIC Correct Answ_initial destination of COPII vesicles from ERES
vesicles can fuse to form larger vesicles and interconnected tubules
vesicular-tubular carriers move towards CGN via cytoskeleton
srves as a sorign station
,Golgi cisternae Correct Answ_3+ large, flattened cisternae
divided into cis, medial, and trans
TGN Correct Answ_transGolgi network
serves as a sorting station
involved in forward transport of materials from Golgi to other compartments
site of secretory vesicle/granule assembly and COPI assembly
glycosylation in the Golgi Correct Answ_cis, medial, and trans cisternae possess unique
glycosyltransferase enzymes that sequentially modify the glycoprotein's core oligosaccharide in
specific ways
other modifications serve as targeting signal for proteins destined for lysosome
ex. alpha-mannosidase I, which removes 3 mannose sugars from the core oligosaccharide
M6P Correct Answ_2 mannose sugars in the core oligosaccharide that were phosphorylated
serves as signal patch for lysosomal targeting via secretory pathways
, what do proteins w/out an M6P do? Correct Answ_packaged into other TGN transport
vesicles or granules destined for pm and extracellular space via the secretory pathway
cisternal progression/maturation model Correct Answ_composition of each subcompartment
changes while moving from cis to trans through stack
CGN matures into cis cisternae, which matures into medial, which matures into trans, etc.
Golgi complex persists overall bc transport vesicles continually move resident Golgi proteins
back to the proper subcompartment and COPII transporting vesicles from ERES and VTCs via
ERGIC that fuse together to form a new CGN
TGN eventually disperses into various vesicles that traffic to endosomes/lysosomes or to pm
lysosome Correct Answ_aka vacuole in plants
digestive organelle, degrades all types of macromolecules and play key role in degradation of
cellular organelles/components (autophagy)
only active at pH 4.6 (maintained by H+ pumps)
resident lysosomal membrane proteins are protected by their CHO groups
products of degradation are transported into cytoplasm and reused by various biosynthetic
pathways
