MCB*2050 Final Exam Key Terms Questions With
Complete Solutions
'Piggyback' nuclear protein import Correct Answers Some
proteins are imported into the nucleus without an NLS. The
nascent protein lacking an NLS binds to an NLS-containing
protein in the cytoplasm. Targeting and import of the protein-
protein complex into the nucleus is mediated by importing
receptors, as per usual.
ABC nuclear lamins Correct Answers Evolutionary related to
proteins that form intermediate filaments in the cytoskeleton
network.
Acceptor membrane compartments Correct Answers A vesicle
(the donor membrane and luminal cargo proteins) fuses with
__________ _________ ___________________.
Acid hydrolase Correct Answers Enzymes found in the
lysosome that are enzymatically active only at low pH (~4.6) of
lysosome interior (lumen). Resident lysosomal membrane
proteins are protected ('shielded') from degradation by attached
lumen-facing carbohydrate groups (added to protein in ER and
Golgi [N-glycosylation]).
alpha helix plug Correct Answers The Sec61 translocon channel
is blocked by this second gate-keeping mechanism. It maintains
ER organelle compartmentalization during protein translocation.
The growing polypeptide forces 'plug' away from channel
,alpha-mannosidase I Correct Answers In cis cisternae, this
enzyme removes 3 mannose sugars from core oligosaccharide of
glycoprotein
Anterograde transport Correct Answers Movement of vesicles
in the forward direction. ER to Golgi (COPII) or Golgi to
endosomes/plasma membrane to endosomes (clathrin).
AP1 and GGA (AP complex) Correct Answers Adaptor coat
proteins that mediate vesicle 'cargo' section (like Sec24 in COPII
at ERES). They also serve as 'linker' during clathrin-coat vesicle
assembly
AP2 Correct Answers An adaptor 'coat' protein which serves as
'linker' during clathrin-coat vesicle assembly
ARC3, MinD and MinE Correct Answers Initial positioning of
FtsZ proteins at equator is mediated by these soluble, stromal
proteins
ARC5 (Accumulation & Replication of Chloroplasts 5) Correct
Answers A cytoplasmic, soluble dynamin-related GTPase
protein that assembles into 'spiral-like' structures that form PD-
ring. PDV1 and PDV2 are bound to this protein.
ARC6 ( Accumulation and Replication of Chloroplasts 6)
Correct Answers The linkage of Z-ring to inner membrane at
chloroplast division site is mediated by this protein.
Arf1 Correct Answers recruitment of AP1/GGA adaptor
proteins from the cytoplasm to TGN surface is mediated by this
,GTPase (regulatory) protein. Upon binding to GTP, a
conformational change occurs which exposes lipid anchor that
directs it from cytoplasm to outer leaflet of TGN membrane.
Also involved in the initiation of COPI-coated vesicle assembly
during retrograde transport within and from the Golgi complex.
ATF6-mediated UPR pathway: Golgi-associated protease
Correct Answers ATF6 transcription factor domain targets to
nucleus via an exposed NLS (not exposed in full-length ATF6)
Autophagy Correct Answers A process in which lysosomes
decompose damaged organelles to reuse their organic
monomers. Essentially the degradation of larger cellular
components/organelles.
Bak and Bax Correct Answers Proper Mfn1/2 binding (e.g.,
prevention of 'self' binding) is regulated by these mitochondrial
outer membrane proteins
Biosynthetic pathway Correct Answers Materials are
transported from the ER to the Golgi, to endosomes and then to
either lysosomes or to the plasma membrane (PM) and extra
cellular space.
Bipartite NLS Correct Answers composed of two short
stretches of basic AAs and a 7-10 AA long 'spacer' sequence.
E.g. -KR[PAATKAGQA]KKKK- in nucleoplasm
Brightfield microscopy Correct Answers Main components:
light source, condenser lens, stage (holding specimen), objective
and ocular (projection) lenses, and 'detector' (eye). Light is
, diffracted by specimen and undiffracted light (e.g. field of view)
focused by objective lens. Image usually captured by video
camera. Easily to manipulate digital images using various
computer software programs using deconvolution. A limitation
is the specimen's poor contrast. Specimens are usually fixed,
embedded for support and then sectioned with a microtome, and
stained with a molecule-specific dye.
bulk-phase endocytosis (pinocytosis) Correct Answers A form
of endocytosis involving the non-specific uptake of extracellular
fluids, plasma membrane proteins and lipids into small vesicles.
PM recycles every ~20-90 min.
C-terminal -KDEL sequence Correct Answers Most resident
soluble ER proteins (e.g, BiP) possess this sequence. It serves as
ER retrieval sorting signal.
C-terminal dilysine (-KKxx)sequence Correct Answers Most
resident ER membrane proteins (e.g., calnexin) possess this
cytoplasmic-facing sequence. It serves as an ER retrieval sorting
signal. This sequence is found on 'escaped' ER membrane
proteins at CGN and is recognized by COPI.
cardiolipin Correct Answers A mitochondrial-specific
membrane phospholipid. The enrichment of this phospholipid at
the constriction site in mitochondrial outer membrane triggers
Drp1 recruitment and assembly.
Cell cycle Correct Answers Series of defined stages in the cell's
life cycle. Two main phases: Interphase and M phase (mitosis)
Complete Solutions
'Piggyback' nuclear protein import Correct Answers Some
proteins are imported into the nucleus without an NLS. The
nascent protein lacking an NLS binds to an NLS-containing
protein in the cytoplasm. Targeting and import of the protein-
protein complex into the nucleus is mediated by importing
receptors, as per usual.
ABC nuclear lamins Correct Answers Evolutionary related to
proteins that form intermediate filaments in the cytoskeleton
network.
Acceptor membrane compartments Correct Answers A vesicle
(the donor membrane and luminal cargo proteins) fuses with
__________ _________ ___________________.
Acid hydrolase Correct Answers Enzymes found in the
lysosome that are enzymatically active only at low pH (~4.6) of
lysosome interior (lumen). Resident lysosomal membrane
proteins are protected ('shielded') from degradation by attached
lumen-facing carbohydrate groups (added to protein in ER and
Golgi [N-glycosylation]).
alpha helix plug Correct Answers The Sec61 translocon channel
is blocked by this second gate-keeping mechanism. It maintains
ER organelle compartmentalization during protein translocation.
The growing polypeptide forces 'plug' away from channel
,alpha-mannosidase I Correct Answers In cis cisternae, this
enzyme removes 3 mannose sugars from core oligosaccharide of
glycoprotein
Anterograde transport Correct Answers Movement of vesicles
in the forward direction. ER to Golgi (COPII) or Golgi to
endosomes/plasma membrane to endosomes (clathrin).
AP1 and GGA (AP complex) Correct Answers Adaptor coat
proteins that mediate vesicle 'cargo' section (like Sec24 in COPII
at ERES). They also serve as 'linker' during clathrin-coat vesicle
assembly
AP2 Correct Answers An adaptor 'coat' protein which serves as
'linker' during clathrin-coat vesicle assembly
ARC3, MinD and MinE Correct Answers Initial positioning of
FtsZ proteins at equator is mediated by these soluble, stromal
proteins
ARC5 (Accumulation & Replication of Chloroplasts 5) Correct
Answers A cytoplasmic, soluble dynamin-related GTPase
protein that assembles into 'spiral-like' structures that form PD-
ring. PDV1 and PDV2 are bound to this protein.
ARC6 ( Accumulation and Replication of Chloroplasts 6)
Correct Answers The linkage of Z-ring to inner membrane at
chloroplast division site is mediated by this protein.
Arf1 Correct Answers recruitment of AP1/GGA adaptor
proteins from the cytoplasm to TGN surface is mediated by this
,GTPase (regulatory) protein. Upon binding to GTP, a
conformational change occurs which exposes lipid anchor that
directs it from cytoplasm to outer leaflet of TGN membrane.
Also involved in the initiation of COPI-coated vesicle assembly
during retrograde transport within and from the Golgi complex.
ATF6-mediated UPR pathway: Golgi-associated protease
Correct Answers ATF6 transcription factor domain targets to
nucleus via an exposed NLS (not exposed in full-length ATF6)
Autophagy Correct Answers A process in which lysosomes
decompose damaged organelles to reuse their organic
monomers. Essentially the degradation of larger cellular
components/organelles.
Bak and Bax Correct Answers Proper Mfn1/2 binding (e.g.,
prevention of 'self' binding) is regulated by these mitochondrial
outer membrane proteins
Biosynthetic pathway Correct Answers Materials are
transported from the ER to the Golgi, to endosomes and then to
either lysosomes or to the plasma membrane (PM) and extra
cellular space.
Bipartite NLS Correct Answers composed of two short
stretches of basic AAs and a 7-10 AA long 'spacer' sequence.
E.g. -KR[PAATKAGQA]KKKK- in nucleoplasm
Brightfield microscopy Correct Answers Main components:
light source, condenser lens, stage (holding specimen), objective
and ocular (projection) lenses, and 'detector' (eye). Light is
, diffracted by specimen and undiffracted light (e.g. field of view)
focused by objective lens. Image usually captured by video
camera. Easily to manipulate digital images using various
computer software programs using deconvolution. A limitation
is the specimen's poor contrast. Specimens are usually fixed,
embedded for support and then sectioned with a microtome, and
stained with a molecule-specific dye.
bulk-phase endocytosis (pinocytosis) Correct Answers A form
of endocytosis involving the non-specific uptake of extracellular
fluids, plasma membrane proteins and lipids into small vesicles.
PM recycles every ~20-90 min.
C-terminal -KDEL sequence Correct Answers Most resident
soluble ER proteins (e.g, BiP) possess this sequence. It serves as
ER retrieval sorting signal.
C-terminal dilysine (-KKxx)sequence Correct Answers Most
resident ER membrane proteins (e.g., calnexin) possess this
cytoplasmic-facing sequence. It serves as an ER retrieval sorting
signal. This sequence is found on 'escaped' ER membrane
proteins at CGN and is recognized by COPI.
cardiolipin Correct Answers A mitochondrial-specific
membrane phospholipid. The enrichment of this phospholipid at
the constriction site in mitochondrial outer membrane triggers
Drp1 recruitment and assembly.
Cell cycle Correct Answers Series of defined stages in the cell's
life cycle. Two main phases: Interphase and M phase (mitosis)
