Chapter 8 : Cell Bio
A control cell that is synthesizing a GFP-labeled version of mannosidase II has fluorescence localized in the numerous Golgi complexes of the cell. Normally, this enzyme is synthesized in the endoplasmic reticulum and moves via transport vesicles to the Golgi complex, where it takes up residence. What would an experimental cell look like if it contained an siRNA that led to the absence of one of the proteins involved in the transport of the enzyme from the ER to the Golgi complex? 1) Fluorescent label is NOT found in the Golgi complex. 2) The GFP-mannosidase II is denatured so there is no fluorescent label anywhere in the cell. 3) Fluorescent label still translocates the Golgi complex completely. 4) Fluorescent label is found only in the endoplasmic reticulum. Option A: 1 Option B: 2 Option C: 3 Option D: 3 and 4 Option E: 1 and 4
1 and 4
Which pH below would be most likely to favor the operation of a lysosomal enzyme? Option A: 8.5 Option B: 7.6 Option C: 4.5 Option D: 11.3 Option E: 6.5
4.5
Which of the following cells would be MOST appropriate to study lysosomes? Option A: A muscle cell carrying out glycolysis Option B: A plant cell undergoing turgor pressure Option C: A white blood cell carrying out phagocytosis Option D: None of the choices is correct
A white blood cell carrying out phagocytosis
Which of the following groups of proteins would probably have a signal sequence? 1) Enzymes found in lysosomes 2) Glycolytic enzymes in bacteria 3) Hormones synthesized in endocrine cells Option A: 2 Option B: Both 1 and 3 are correct Option C: 3 Option D: 1
Both 1 and 3 are correct
Where does glycosylation take place? 1) Lysosomes 2) Golgi Complex 3) Rough Endoplasmic Reticulum Option A: Lysosomes Option B: 2 Option C: 3 Option D: Both 2 and 3 are correct Option E: All of the choices are correct
Both 2 and 3 are correct
Contrary to COPII-coated vesicles, COPI-coated vesicles: 1) are implicated in anterograde movement of proteins. 2) are implicated in retrograde movement of proteins. 3) contain GTP-binding proteins. Option A: 3 Option B: 1 Option C: Both 2 and 3 are correct Option D: 2
Both 2 and 3 are correct; are implicated in retrograde movement of proteins and contain GTP-binding proteins
Of the following, which would least likely to be found in lysosomes? Option A: DNA Option B: Collagenase Option C: Phospholipase Option D: Cathepsin
DNA
A researcher used a radioactive label to track the pathway of an enzyme secreted by pancreatic cells. What is the MOST likely pathway? Option A: Golgi → ER → lysosome Option B: ER → Golgi → vesicles that fuse with plasma membrane Option C: Golgi → ER → vesicles that fuse with plasma membrane Option D: ER → Golgi → lysosome
ER → Golgi → vesicles that fuse with plasma membrane
What enzyme is the rate-controlling enzyme in cholesterol biosynthesis? Option A: HMG CoA oxidase Option B: HMG CoA reductase Option C: LDL reductase Option D: cholesterol synthase Option E: HMG cholesterol synthase
HMG CoA reducatse
_____________ residues act as an "address" for delivery of proteins to lysosomes Option A: Mannose 6-phosphate Option B: selenocysteine Option C: ubiquitin Option D: methionine
Mannose 6-phosphate
Cells are infected with a vesicular stomatitis virus (VSV) strain in which a viral gene (VSVG) is fused to the green fluorescent protein gene. When the chimeric protein is synthesized, what pathway does it follow from synthesis until it leaves the cell? Option A: RER, Golgi complex, plasma membrane, viral envelopes Option B: RER, Golgi complex, viral envelopes, plasma membrane Option C: Golgi complex, RER, plasma membrane, viral envelopes Option D: RER, Golgi complex, mitochondria, plasma membrane, viral envelopes Option E: RER, mitochondria, Golgi complex, plasma membrane, viral envelopes
RER, golgi complex, plasma membrane, viral envelopes
A cellular phenomenon called _________ is a process in which cells produce small RNAs that bind to specific mRNAs and inhibit the translation of these mRNAs into proteins. Option A: RNAi Option B: cRNAs Option C: RNAi and RNA interference Option D: RNA interference Option E: RNAa
RNAi and RNA interference
The interaction between the membranes of vesicles and their target compartment is mediated by which proteins below? Option A: ARF1s Option B: SNAREs Option C: SNARFs Option D: Sar1s Option E: Rafs
SNAREs
What evidence suggests that the translocon, by itself, can properly orient transmembrane segments? Option A: Studies performed with purified components in cell-free systems show that the translocon, by itself, is capable of properly orienting transmembrane segments. Option B: Reconstituted translocons properly oriented membrane proteins in a natural membrane. Option C: Translocons orient proteins in red blood cells when exposed to them. Option D: Translocons bind to proteins in vitro. Option E: When translocons are missing, membrane proteins are not appropriately oriented.
Studies performed with purified components in cell-free systems show that the translocon, by itself, is capable of properly orienting transmembrane segments
How are integral membrane proteins thought to enter the lipid bilayer? Option A: They insert into the membrane from the RER lumen after their synthesis is complete. Option B: The aqueous translocon channel seems to have a gate that continuously opens and closes, giving each nascent polypeptide segment a chance to partition itself into the lipid bilayer's hydrophobic core. Option C: They insert into the membrane from the cytosol after their synthesis is complete. Option D: It is thought that they burrow into the lipid bilayer. Option E: It is thought that they are enzymatically implanted in the lipid bilayer
The aqueous translocon channel seems to have a gate that continuously opens and closes, giving each nascent polypeptide segment a chance to partition itslef into the lipid bilayer's hydrophobic core
Phospholipids are made by integral ER membrane enzymes whose active sites face the cytosol and they are inserted into the outer (cytoplasmic) leaflet of the ER membrane. How then do lipids destined for the luminal leaflet of the ER membrane get there? Option A: They diffuse freely into the luminal leaflet. Option B: There are enzymes called flippases that flip these lipids later into the opposite leaflet. Option C: They are disassembled on the cytoplasmic side and reassembled on the luminal side. Option D: They move to the cytoplasmic leaflet by osmosis. Option E: There are enzymes called translocases that flip these lipids later into the opposite leaflet.
There are enzymes called flippases that flip these lipids later into their opposite leaflet
Fibroblasts from familial hypercholesterolemia patients were placed in culture medium in the presence of cholesterol-containing lipoproteins like LDL. What effect, if any, did this have on the fibroblasts? Option A: there was no effect Option B: decreased levels of HMG CoA reductase Option C: increased levels of HMG CoA reductase Option D: decrease in cholesterol synthesis Option E: increased levels of HMG CoA oxidase
There was no effect
What would happen to the movement of vesicles toward their eventual target if a microtubule inhibitor like colchicine were added to the cells? Option A: The vesicles would disintegrate. Option B: The vesicles would move faster. Option C: Vesicle movement would slow or stop. Option D: Vesicles will shrink. Option E: Vesicles will swell.
Vescile movement would slow or stop
A lipid species (consider the phosphoinositides) can have a dynamic regulatory role because _______. Option A: it can be rapidly formed by enzymes localized at particular places within the cell Option B: it can be rapidly formed by enzymes localized at particular times within the cell Option C: it can be rapidly destroyed by enzymes localized at particular places within the cell Option D: it can be rapidly destroyed by enzymes localized at particular times within the cell Option E: all of the choices are correct
all of the choices are correct
In receptor down-regulation, signaling receptors are _____________________. Option A: covalently attached to ubiquitin Option B: subjected to endocytosis Option C: internalized and destroyed Option D: all of the choices are correct
all of the choices are correct
What components below are selected for transport by vesicles originating in the Golgi complex? Option A: secretory proteins Option B: lysosomal proteins Option C: proteins required to dock the vesicle to an acceptor membrane Option D: proteins required to target the vesicle to an acceptor membrane Option E: all of these components
all of these components
To what residue of a polypeptide are N-linked oligosaccharide chains attached as that polypeptide enters the RER lumen through the translocon? Option A: arginine Option B: asparagine Option C: serine Option D: threonine Option E: ninhydrin
asparagine
What process is responsible for organelle turnover in the cell and carries out the regulated destruction of the cell's own organelles for the purpose of recycling the components of which they are made? Option A: autolysis Option B: autophagolysosome Option C: apoptosis Option D: autophagy Option E: autonomy
autophagy
Studies of cell physiology that occur in test tubes that do NOT contain whole cells are called ______. Option A: in vivo systems Option B: cell-free systems Option C: test tube systems Option D: onsite systems Option E: cellonic systems
cell-free systems
What are the two sites within a cell at which protein synthesis is generally thought to occur? Option A: cytosolic surface of RER and cisternal surface of RER Option B: cytosolic surface of RER and free ribosomes Option C: cisternal surface of RER and free ribosomes Option D: free ribosomes and cytosolic surface of SER Option E: cytosolic surface of RER and cytosolic surface of SER
cytostolic surface of RER and free ribosomes
Asymmetry of cellular membranes is established initially in the _____________. Option A: nucleus Option B: mitochondria Option C: endoplasmic reticulum Option D: chloroplast
endoplasmic reticulum
Fusion of a secretory vesicle with the plasma membrane and discharge of its contents is called ___________. Option A: endocytosis Option B: exocytosis Option C: cisternal maturation Option D: ER-associated degradation
exocytosis
People who have profoundly elevated serum cholesterol levels, develop severely blocked (atherosclerotic) arteries, and usually die from heart attack before the age of 20, are likely to suffer from which of the following diseases? Option A: familial hypercholesterolemia Option B: familial hypocholesterolemia Option C: inherited cholesterol inflammation Option D: familial atheriasis Option E: hemophilia
familial hypERcholesterolemia
Which procedure below would lead to the visualization of the dynamic movements of specific proteins as they move through a single living cell? The proteins can be seen through the microscope eyepiece and the cells do NOT have to be killed for the protein to be detected. Option A: pulse-chase Option B: fusion of the green fluorescent protein gene to the protein that is to be tracked through the cell Option C: fusion of the green fluorescent protein gene to the gene encoding the protein to be tracked through the cell Option D: pulse-chase using fluorescent antibodies Option E: all of the choices are correct
fusion of the green fluorescent protein gene to the protein that is to be tracked through the cell
In phagocytosis, the phagosome fuses with which organelle, leading to digestion of engulfed material? Option A: Golgi complex Option B: endoplasmic reticulum Option C: lysosome Option D: mitochondria
lysosome
How is movement of vesicular-tubular carriers directed from the ERGIC to the Golgi complex? Option A: random diffusion Option B: fast vesicle propulsion Option C: a slingshot mechanism Option D: movement occurs on microtubule tracks
movement occurs on the microtubule tracks
What is the arrangement of organelles in a secretory cell from the basal end to the apical end, an arrangement that reflects the flow of secretory products from synthesis to discharge? Option A: nucleus and RER - SER - Golgi complex - secretory vesicles Option B: Golgi complex - nucleus and RER - SER - secretory vesicles Option C: nucleus and RER - Golgi complex - SER - secretory vesicles Option D: SER - nucleus and RER - Golgi complex - secretory vesicles Option E: secretory vesicles - nucleus and RER - SER - Golgi complex
nucleus and RER - SER - Golgi complex - secretory vesicles
Which of the proteins below is(are) NOT made on the membrane-bound ribosomes of the RER? Option A: peripheral proteins of the inner surface of the plasma membrane Option B: soluble lysosomal proteins Option C: vacuolar enzymes Option D: proteins of the extracellular matrix Option E: all of the choices are correct
peripheral proteins of the inner surface of the plasma membrane
The two separate (basic) categories of uptake of extracellular materials into cytoplasmic vesicles are ______ and ______. Option A: phagocytosis, exocytosis Option B: pinocytosis, exocytosis Option C: phagocytosis, endocytosis Option D: pinocytosis, endocytosis Option E: exocytosis, endocytosis
phagocytosis, endocytosis
What is the name for a brief incubation of a tissue with radioactivity during which labeled amino acids are incorporated into protein? Option A: chase Option B: pulse Option C: pulse-chase Option D: labelard Option E: statin
pulse
A tissue has been briefly labeled with radiolabeled amino acids. It is then transferred to a medium containing unlabeled amino acids. This can be done several times with different tissue samples for varying periods of time. What is the entire procedure called? Option A: chase Option B: pulse Option C: pulse-chase Option D: labelard Option E: statin
pulse-chase
Vesicles that move through the Golgi complex from a trans-donor to a cis-acceptor membrane are said to move in a(n) __________ direction. Option A: astrograde Option B: anterograde Option C: retrograde Option D: awful grade Option E: verigrade
retrograde
What binds to the signal of a receptor and the clathrin coat helping the receptor to be trapped in coated pits prior to endocytosis? Option A: the LDL receptor Option B: the AP2 adaptor Option C: the NPXY signal Option D: the AP3 adaptor Option E: ATP synthase
the AP2 adaptor
What allows smooth and rough vesicles (microsomes) to be readily separated by density gradient centrifugation? Option A: their size differences Option B: their differences in lipid composition Option C: their differences in color Option D: their differences in density Option E: their differences in water content
the differences in density
With what structure is the RER often seen to be continuous, as seen by its association with ribosomes? Option A: the inner membrane of the nuclear envelope Option B: the outer membrane of the nuclear envelope Option C: the outer mitochondrial membrane Option D: the outer chloroplast membrane Option E: the Golgi complex
the outer membrane of the nuclear envelope
What determines the sequence of sugar addition to glycoproteins traveling through the Golgi complex? Option A: Nothing - the sequence is random Option B: the spatial arrangement of specific glycosyltransferases that contact proteins as they pass through the Golgi complex Option C: the concentration of sugars in the Golgi complex Option D: the sequence of nucleotides in the Golgi complex
the spatial arrangement of specific glycosyltransferases that contact proteins as they pass through the Golgi complex
Which of the following is triggered by the accumulation of misfolded proteins in the ER? Option A: reduced transcription of rRNA Option B: the unfolded protein response Option C: inhibition of the trans Golgi network Option D: activation of the cis Golgi network
the unfolded protein response
The accumulation of misfolded proteins in the ER is a potentially lethal situation and thus causes the triggering of what process? Option A: the unfolded protein response (UPR) Option B: the post-transcriptional response Option C: the polysomal response Option D: the proteasomal response Option E: the intracellular protein response
the unfolded protein response (UPR)
The ____________ functions as a major sorting station, directing proteins to various destinations. Option A: trans Golgi network Option B: rough ER Option C: lysosome Option D: ribosome
trans Golgi network
When cells are homogenized, the cytomembrane system is broken into fragments, the ends of which can fuse to form small membranous spheres called ________. Option A: vacuoles Option B: victuals Option C: vesicles Option D: nuclei Option E: endosomes
vesicles
