MCB 2050 Pt. 2 Questions With Complete Solutions
All mitochondrial proteins possess a unique targeting sequence
T/F Correct Answers True.
specific AA sequence mediates protein targeting from cytosol to
surface of mitochondria
AND
to specific mitochondrial subcomparment (out membrane,
intermembrane space, inner membrane, matrix)
AP2 Correct Answers soluble adaptor protein
- forms inner layer of vesicle 'coat'
- recruits clathrin triskelions from cytosol to form outer
scaffolding of coat of growing vesicle
Are there other TIM complexes? What do they do? Correct
Answers Yes, they are involved in different sub-mitochondrial
targeting pathways
TIM22 complex is responsible for insertion and assembly of
inner membrane proteins
-proteins pass from TOM to TIM22 and are then transferred
laterally into lipid bilayer
Asymmetry of proteins and lipids are established in ER and
change throughout the endomembrane system.
T/F Correct Answers False, they are maintained throughout the
endomembrane system
ie. if it is an integral membrane protein, will remain so always,
same for if peripheral MP
Autophagy is a selective process
,T/F Correct Answers True.
organelles/components to be degraded are tagged on cell surface
for autophagy
biggest molecule that can move freely through NPC Correct
Answers 40kDa, anything larger is selectively
imported/exported
Biosynthetic pathway Correct Answers 1. lysosomal proteins
synthesized and initially N-glycosylated in RER, transported to
Golgi
2. at cis Golgi cisternae, glycosylated lysosomal proteins are
further modified (add M6P to core oligosaccharide)
3. in TGN, M6P lysosomal proteins recognized by M6P receptor
(lumenal-facing domain of M6P receptr binds to M6P group in
TGN lumen)
4. M6P receptor mediates subsequent concentrations of
lysosomal proteins into clathrin-coated vesicles
5. cytosolic-facing domain of M6P receptor binds to GGA
adaptor 'coat' proteins
6. GGA proteins serve as 'linkers' during clathrin-coated vesicle
assembly
biosynthetic pathway Correct Answers ER to Golgi to
endosomes to lysosomes (vacuoles in plants) to the PM
Bipartite NLS Correct Answers KR[XXXXXXXXXX]KKKK,
two short stretches of basic AA and 7-10 AA spacer sequence
blue light is Correct Answers short wavelength (427nm)
,bright-field microscopy components Correct Answers light
source, condenser lens, stage, objective and ocular lenses
bright-field microscopy Correct Answers image captured by
digital camera, allows living cells to be viewed without photo
damage and image can be manipulated by computers to remove
background blurry light
bright-field microscopy Correct Answers light diffracted by
specimen and undiffracted light focused by objective lens
Bulk-phase endocytosis Correct Answers responsible for non-
specific uptake of extracellular fluids and plasma membrane
protein turnover
Can membranes form de novo (brand new)? Correct Answers
No, all membranes arise form pre-existing membranes
Can nascent ER membrane proteins and lipids traffic to other
membranes? How? Correct Answers Yes, through lateral
diffusion through the bilayer or to other 'downstream' organelles
of the endomembrane system via vesicle transport
Can resident ER proteins enter Golgi-destined vesicles? Correct
Answers They can however they usually are prevented from
doing so as most proteins need to contain unique targeting
signals and receptors in order to be chosen for transport
cell biology Correct Answers multidisciplinary study of
composition, structure and function of various subcellular
organelles
, chromosome location... Correct Answers often related to its
activity
chromosomes Correct Answers organized in discrete
subdomains during interphase within nucleus
cis Golgi Network (CGN) Correct Answers - located at cis face
of GC
- consists of interconnected network of tubules and vesicles
adjacent to ERES
- sorting station: destination for COPII vesicles from ERES and
site of COPI vesicle assembly for retrograde transport OR
anterograde transport as CGN matures into rest of GC
Cisternal progression/maturation model Correct Answers most
favoured model
- Golgi subcompartments considered dynamic (moves from cis
to trans)
- composition of compartments change while moving cis to trans
- golgi complex persists overall because COPI vesicles
continually move resident golgi proteins 'back' to proper
comparment
- COPII vesicles that arrive at CGN fuse together to form new
CGN
- new CGN moves 'forward' in stack and matures into cis
cisternae etc.
- chemical composition of each cisternae constantly changes
- TGN disperses into various types of vesicles to different
compartments of endomembrane system
All mitochondrial proteins possess a unique targeting sequence
T/F Correct Answers True.
specific AA sequence mediates protein targeting from cytosol to
surface of mitochondria
AND
to specific mitochondrial subcomparment (out membrane,
intermembrane space, inner membrane, matrix)
AP2 Correct Answers soluble adaptor protein
- forms inner layer of vesicle 'coat'
- recruits clathrin triskelions from cytosol to form outer
scaffolding of coat of growing vesicle
Are there other TIM complexes? What do they do? Correct
Answers Yes, they are involved in different sub-mitochondrial
targeting pathways
TIM22 complex is responsible for insertion and assembly of
inner membrane proteins
-proteins pass from TOM to TIM22 and are then transferred
laterally into lipid bilayer
Asymmetry of proteins and lipids are established in ER and
change throughout the endomembrane system.
T/F Correct Answers False, they are maintained throughout the
endomembrane system
ie. if it is an integral membrane protein, will remain so always,
same for if peripheral MP
Autophagy is a selective process
,T/F Correct Answers True.
organelles/components to be degraded are tagged on cell surface
for autophagy
biggest molecule that can move freely through NPC Correct
Answers 40kDa, anything larger is selectively
imported/exported
Biosynthetic pathway Correct Answers 1. lysosomal proteins
synthesized and initially N-glycosylated in RER, transported to
Golgi
2. at cis Golgi cisternae, glycosylated lysosomal proteins are
further modified (add M6P to core oligosaccharide)
3. in TGN, M6P lysosomal proteins recognized by M6P receptor
(lumenal-facing domain of M6P receptr binds to M6P group in
TGN lumen)
4. M6P receptor mediates subsequent concentrations of
lysosomal proteins into clathrin-coated vesicles
5. cytosolic-facing domain of M6P receptor binds to GGA
adaptor 'coat' proteins
6. GGA proteins serve as 'linkers' during clathrin-coated vesicle
assembly
biosynthetic pathway Correct Answers ER to Golgi to
endosomes to lysosomes (vacuoles in plants) to the PM
Bipartite NLS Correct Answers KR[XXXXXXXXXX]KKKK,
two short stretches of basic AA and 7-10 AA spacer sequence
blue light is Correct Answers short wavelength (427nm)
,bright-field microscopy components Correct Answers light
source, condenser lens, stage, objective and ocular lenses
bright-field microscopy Correct Answers image captured by
digital camera, allows living cells to be viewed without photo
damage and image can be manipulated by computers to remove
background blurry light
bright-field microscopy Correct Answers light diffracted by
specimen and undiffracted light focused by objective lens
Bulk-phase endocytosis Correct Answers responsible for non-
specific uptake of extracellular fluids and plasma membrane
protein turnover
Can membranes form de novo (brand new)? Correct Answers
No, all membranes arise form pre-existing membranes
Can nascent ER membrane proteins and lipids traffic to other
membranes? How? Correct Answers Yes, through lateral
diffusion through the bilayer or to other 'downstream' organelles
of the endomembrane system via vesicle transport
Can resident ER proteins enter Golgi-destined vesicles? Correct
Answers They can however they usually are prevented from
doing so as most proteins need to contain unique targeting
signals and receptors in order to be chosen for transport
cell biology Correct Answers multidisciplinary study of
composition, structure and function of various subcellular
organelles
, chromosome location... Correct Answers often related to its
activity
chromosomes Correct Answers organized in discrete
subdomains during interphase within nucleus
cis Golgi Network (CGN) Correct Answers - located at cis face
of GC
- consists of interconnected network of tubules and vesicles
adjacent to ERES
- sorting station: destination for COPII vesicles from ERES and
site of COPI vesicle assembly for retrograde transport OR
anterograde transport as CGN matures into rest of GC
Cisternal progression/maturation model Correct Answers most
favoured model
- Golgi subcompartments considered dynamic (moves from cis
to trans)
- composition of compartments change while moving cis to trans
- golgi complex persists overall because COPI vesicles
continually move resident golgi proteins 'back' to proper
comparment
- COPII vesicles that arrive at CGN fuse together to form new
CGN
- new CGN moves 'forward' in stack and matures into cis
cisternae etc.
- chemical composition of each cisternae constantly changes
- TGN disperses into various types of vesicles to different
compartments of endomembrane system
