Bio chapter 8
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? A Option A: RER, Golgi complex, plasma membrane, viral envelopes B Option B: RER, Golgi complex, viral envelopes, plasma membrane C Option C: Golgi complex, RER, plasma membrane, viral envelopes D Option D: RER, Golgi complex, mitochondria, plasma membrane, viral envelopes E Option E: RER, mitochondria, Golgi complex, plasma membrane, viral envelopes
A
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? A Option A: there was no effect B Option B: decreased levels of HMG CoA reductase C Option C: increased levels of HMG CoA reductase D Option D: decrease in cholesterol synthesis E Option E: increased levels of HMG CoA oxidase
A
Of the following, which would least likely to be found in lysosomes? A Option A: DNA B Option B: Collagenase C Option C: Phospholipase D Option D: Cathepsin
A
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? A Option A: familial hypercholesterolemia B Option B: familial hypocholesterolemia C Option C: inherited cholesterol inflammation D Option D: familial atheriasis E Option E: hemophilia
A
The ____________ functions as a major sorting station, directing proteins to various destinations. A Option A: trans Golgi network B Option B: rough ER C Option C: lysosome D Option D: ribosome
A
The accumulation of misfolded proteins in the ER is a potentially lethal situation and thus causes the triggering of what process? A Option A: the unfolded protein response (UPR) B Option B: the post-transcriptional response C Option C: the polysomal response D Option D: the proteasomal response E Option E: the intracellular protein respons
A
What evidence suggests that the translocon, by itself, can properly orient transmembrane segments? A Option A: Studies performed with purified components in cell-free systems show that the translocon, by itself, is capable of properly orienting transmembrane segments. B Option B: Reconstituted translocons properly oriented membrane proteins in a natural membrane. C Option C: Translocons orient proteins in red blood cells when exposed to them. D Option D: Translocons bind to proteins in vitro. E Option E: When translocons are missing, membrane proteins are not appropriately oriented.
A
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? A Option A: nucleus and RER - SER - Golgi complex - secretory vesicles B Option B: Golgi complex - nucleus and RER - SER - secretory vesicles C Option C: nucleus and RER - Golgi complex - SER - secretory vesicles D Option D: SER - nucleus and RER - Golgi complex - secretory vesicles E Option E: secretory vesicles - nucleus and RER - SER - Golgi complex
A
Which of the proteins below is(are) NOT made on the membrane-bound ribosomes of the RER? A Option A: peripheral proteins of the inner surface of the plasma membrane B Option B: soluble lysosomal proteins C Option C: vacuolar enzymes D Option D: proteins of the extracellular matrix E Option E: all of the choices are correct
A
_____________ residues act as an "address" for delivery of proteins to lysosomes A Option A: Mannose 6-phosphate B Option B: selenocysteine C Option C: ubiquitin D Option D: methionine
A
A researcher used a radioactive label to track the pathway of an enzyme secreted by pancreatic cells. What is the MOST likely pathway? A Option A: Golgi → ER → lysosome B Option B: ER → Golgi → vesicles that fuse with plasma membrane C Option C: Golgi → ER → vesicles that fuse with plasma membrane D Option D: ER → Golgi → lysosome
B
Fusion of a secretory vesicle with the plasma membrane and discharge of its contents is called ___________. A Option A: endocytosis B Option B: exocytosis C Option C: cisternal maturation D Option D: ER-associated degradation
B
How are integral membrane proteins thought to enter the lipid bilayer? A Option A: They insert into the membrane from the RER lumen after their synthesis is complete. B 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. C Option C: They insert into the membrane from the cytosol after their synthesis is complete. D Option D: It is thought that they burrow into the lipid bilayer. E Option E: It is thought that they are enzymatically implanted in the lipid bilayer.
B
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? A Option A: They diffuse freely into the luminal leaflet. B Option B: There are enzymes called flippases that flip these lipids later into the opposite leaflet. C Option C: They are disassembled on the cytoplasmic side and reassembled on the luminal side. D Option D: They move to the cytoplasmic leaflet by osmosis. E Option E: There are enzymes called translocases that flip these lipids later into the opposite leaflet.
B
Studies of cell physiology that occur in test tubes that do NOT contain whole cells are called ______. A Option A: in vivo systems B Option B: cell-free systems C Option C: test tube systems D Option D: onsite systems E Option E: cellonic systems
B
The interaction between the membranes of vesicles and their target compartment is mediated by which proteins below? A Option A: ARF1s B Option B: SNAREs C Option C: SNARFs D Option D: Sar1s E Option E: Rafs
B
To what residue of a polypeptide are N-linked oligosaccharide chains attached as that polypeptide enters the RER lumen through the translocon? A Option A: arginine B Option B: asparagine C Option C: serine D Option D: threonine E Option E: ninhydrin
B
What are the two sites within a cell at which protein synthesis is generally thought to occur? A Option A: cytosolic surface of RER and cisternal surface of RER B Option B: cytosolic surface of RER and free ribosomes C Option C: cisternal surface of RER and free ribosomes D Option D: free ribosomes and cytosolic surface of SER E Option E: cytosolic surface of RER and cytosolic surface of SER
B
What binds to the signal of a receptor and the clathrin coat helping the receptor to be trapped in coated pits prior to endocytosis? A Option A: the LDL receptor B Option B: the AP2 adaptor C Option C: the NPXY signal D Option D: the AP3 adaptor E Option E: ATP synthase
B
What determines the sequence of sugar addition to glycoproteins traveling through the Golgi complex? A Option A: Nothing - the sequence is random B Option B: the spatial arrangement of specific glycosyltransferases that contact proteins as they pass through the Golgi complex C Option C: the concentration of sugars in the Golgi complex D Option D: the sequence of nucleotides in the Golgi complex
B
What enzyme is the rate-controlling enzyme in cholesterol biosynthesis? A Option A: HMG CoA oxidase B Option B: HMG CoA reductase C Option C: LDL reductase D Option D: cholesterol synthase E Option E: HMG cholesterol synthase
B
What is the name for a brief incubation of a tissue with radioactivity during which labeled amino acids are incorporated into protein? A Option A: chase B Option B: pulse C Option C: pulse-chase D Option D: labelard E Option E: statin
B
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 A Option A: 2 B Option B: Both 1 and 3 are correct C Option C: 3 D Option D: 1
B
Which of the following is triggered by the accumulation of misfolded proteins in the ER? A Option A: reduced transcription of rRNA B Option B: the unfolded protein response C Option C: inhibition of the trans Golgi network D Option D: activation of the cis Golgi network
B
With what structure is the RER often seen to be continuous, as seen by its association with ribosomes? A Option A: the inner membrane of the nuclear envelope B Option B: the outer membrane of the nuclear envelope C Option C: the outer mitochondrial membrane D Option D: the outer chloroplast membrane E Option E: the Golgi complex
B
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. A Option A: RNAi B Option B: cRNAs C Option C: RNAi and RNA interference D Option D: RNA interference E Option E: RNAa
C
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? A Option A: chase B Option B: pulse C Option C: pulse-chase D Option D: labelard E Option E: statin
C
Asymmetry of cellular membranes is established initially in the _____________. A Option A: nucleus B Option B: mitochondria C Option C: endoplasmic reticulum D Option D: chloroplast
C
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. A Option A: 3 B Option B: 1 C Option C: Both 2 and 3 are correct D Option D: 2
C
In phagocytosis, the phagosome fuses with which organelle, leading to digestion of engulfed material? A Option A: Golgi complex B Option B: endoplasmic reticulum C Option C: lysosome D Option D: mitochondria
C
The two separate (basic) categories of uptake of extracellular materials into cytoplasmic vesicles are ______ and ______. A Option A: phagocytosis, exocytosis B Option B: pinocytosis, exocytosis C Option C: phagocytosis, endocytosis D Option D: pinocytosis, endocytosis E Option E: exocytosis, endocytosis
C
Vesicles that move through the Golgi complex from a trans-donor to a cis-acceptor membrane are said to move in a(n) __________ direction. A Option A: astrograde B Option B: anterograde C Option C: retrograde D Option D: awful grade E Option E: verigrade
C
What would happen to the movement of vesicles toward their eventual target if a microtubule inhibitor like colchicine were added to the cells? A Option A: The vesicles would disintegrate. B Option B: The vesicles would move faster. C Option C: Vesicle movement would slow or stop. D Option D: Vesicles will shrink. E Option E: Vesicles will swell.
C
When cells are homogenized, the cytomembrane system is broken into fragments, the ends of which can fuse to form small membranous spheres called ________. A Option A: vacuoles B Option B: victuals C Option C: vesicles D Option D: nuclei E Option E: endosomes
C
Which of the following cells would be MOST appropriate to study lysosomes? A Option A: A muscle cell carrying out glycolysis B Option B: A plant cell undergoing turgor pressure C Option C: A white blood cell carrying out phagocytosis D Option D: None of the choices is correct
C
Which pH below would be most likely to favor the operation of a lysosomal enzyme? A Option A: 8.5 B Option B: 7.6 C Option C: 4.5 D Option D: 11.3 E Option E: 6.5
C
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. A Option A: pulse-chase B Option B: fusion of the green fluorescent protein gene to the protein that is to be tracked through the cell C Option C: fusion of the green fluorescent protein gene to the gene encoding the protein to be tracked through the cell D Option D: pulse-chase using fluorescent antibodies E Option E: all of the choices are correct
C
How is movement of vesicular-tubular carriers directed from the ERGIC to the Golgi complex? A Option A: random diffusion B Option B: fast vesicle propulsion C Option C: a slingshot mechanism D Option D: movement occurs on microtubule tracks
D
In receptor down-regulation, signaling receptors are _____________________. A Option A: covalently attached to ubiquitin B Option B: subjected to endocytosis C Option C: internalized and destroyed D Option D: all of the choices are correct
D
What allows smooth and rough vesicles (microsomes) to be readily separated by density gradient centrifugation? A Option A: their size differences B Option B: their differences in lipid composition C Option C: their differences in color D Option D: their differences in density E Option E: their differences in water content
D
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? A Option A: autolysis B Option B: autophagolysosome C Option C: apoptosis D Option D: autophagy E Option E: autonomy
D
Where does glycosylation take place? 1) Lysosomes 2) Golgi Complex 3) Rough Endoplasmic Reticulum A Option A: 1 B Option B: 2 C Option C: 3 D Option D: Both 2 and 3 are correct E Option E: All of the choices are correct
D
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. A Option A: 1 B Option B: 2 C Option C: 3 D Option D: 3 and 4 E Option E: 1 and 4
E
A lipid species (consider the phosphoinositides) can have a dynamic regulatory role because _______. A Option A: it can be rapidly formed by enzymes localized at particular places within the cell B Option B: it can be rapidly formed by enzymes localized at particular times within the cell C Option C: it can be rapidly destroyed by enzymes localized at particular places within the cell D Option D: it can be rapidly destroyed by enzymes localized at particular times within the cell E Option E: all of the choices are correct
E
What components below are selected for transport by vesicles originating in the Golgi complex? A Option A: secretory proteins B Option B: lysosomal proteins C Option C: proteins required to dock the vesicle to an acceptor membrane D Option D: proteins required to target the vesicle to an acceptor membrane E Option E: all of these components
E
