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Molec Cell Biology Practice Test Q&As

Question: Regulatory secretion of hormones would be associated with ________ at the transface of the Golgi.
A: microsomes
B: non-clathrin vesicles
C: lysosomes
D: endosomes
E: clathrin-coated vesicles

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clathrin-coated vesicles

Question: The organelle of plant cells that is analogous to the lysosome in animal cells is the
A: endosome.
B: vacuole.
C: microsome.
D: triskelion.
E: lysosome.

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vacuole.

Question: All of the following statements about cellular trafficking are true except
A: movement may be mediated by microtubules.
B: COPI-coated vesicles move materials from Golgi to the secretory vesicle.
C: tethering proteins mediate docking between target and vesicle.
D: v-SNAREs occur in vesicles; t-SNAREs occur on target sites.
E: COPII-coated vesicles move materials from ER to Golgi.

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COPI-coated vesicles move materials from Golgi to the secretory vesicle.

Question: Microsomes are
A: artifacts generated during homogenization of cells.
B: organelles of eukaryotic cells.
C: structures observed in cyanobacteria.
D: organelles through which electrons cannot pass.
E: too small to be seen with an electron microscope.

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artifacts generated during homogenization of cells.

Question: All of the following are part of the endomembrane system, except the
A: peroxisomes.
B: Golgi body.
C: endosomes.
D: lysosomes.
E: Neither lysosomes nor Golgi body are part of the endomembrane system.

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peroxisomes.

Question: The endoplasmic reticulum is a site for
A: potassium storage in muscle cells.
B: N-linked glycosylation of polypeptides.
C: drug detoxification by catalase.
D: addition of lipid residues.
E: N-linked glycosylation of polypeptides and drug detoxification by catalase.

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N-linked glycosylation of polypeptides.

Question: Each of the following is an endoplasmic reticulum function except
A: the assembly of multimeric proteins.
B: peptide folding.
C: addition of carbohydrate to proteins to make glycoproteins.
D: the export of protein that cannot be folded into the cytoplasm for destruction.
E: All are endoplasmic reticulum functions.

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All are endoplasmic reticulum functions.

Question: Which of the following statements about the smooth endoplasmic reticulum is/are correct?
A: Liver cells are abundant in SER.
B: The testes and ovaries are tissue types whose cells are abundant in SER.
C: The SER is the primary location for synthesis of membrane-bound proteins.
D: Cholesterol is made in the SER.
E: The luminal face of the SER is the main site at which membrane lipids are synthesized.
F: Phospholipids are synthesized from cytosolic water soluble precursor molecules.
G: Flippases are the enzymes that allow lateral movement of a lipid within a leaflet.

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The following statements about the smooth endoplasmic reticulum are correct
Cholesterol is made in the SER
The testes and ovaries are tissue types whose cells are abundant in SER
Phospholipids are synthesized from cytosolic water soluble precursor molecules
Liver cells are abundant in SER

Question: How do proteins become embedded in the membrane of the endoplasmic reticulum?
How do membrane-bound proteins become embedded in the membrane of the endoplasmic reticulum?
A: by splicing of proteins on either side of the ER membrane
B: via stop- and start-transfer sequences that stop and start translocation of a polypeptide through the ER membrane, resulting in transmembrane proteins
C: by post-translational import can results in a transmembrane ER protein
D: by protein chaperones that insert polypeptides into the ER membrane
E: via transit sequences that target polypeptides made in the cytosol for the ER membrane

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via stop- and start-transfer sequences that stop and start translocation of a polypeptide through the ER membrane, resulting in transmembrane proteins

Question: Ribosomes that do not anchor on the surface of the rough endoplasmic reticulum duringtranslation mostprobably
A: have a defect in ribosomal proteins that allow attachment to the surface.
B: do not make the appropriate anchor protein.
C: are synthesizing cytoplasmic proteins.
D: have a signal peptidase error.
E: All of the above are probable reasons.

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are synthesizing cytoplasmic proteins.

Question: In the Golgi complex, __________.
A: proteins are N-glycosylated
B: the anterograde transport system is used to move vesicles back to the ER
C: carbohydrate side chains of glycoproteins are modified
D: proteins are synthesized

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carbohydrate side chains of glycoproteins are modified

Question: Compared with the trans-Golgi proteins, the cis-Golgi proteins would
A: contain sialic acid.
B: be glycosylated only.
C: be glycosylated and contain amino acid modifications.
D: be identical.
E: be shorter in length.

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be glycosylated only.

Question: A protein is destined to be secreted from a cell. In which of the following organelles would you expect to find the protein first?
A: secretory vesicle
B: Golgi apparatus
C: lysosome
D: endosome

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Golgi apparatus

Question: A radioactively labeled protein is made by cells and followed through the various organelles in the secretory pathway. After six hours, all of the radioactivity is still primarily in the Golgi apparatus. This suggests that the
A) protein was not translated by the ribosomes.
B) protein does not possess a signal peptide for localization within the lumen of the rough endoplasmic reticulum.
C) protein possesses a signal for localization within the Golgi apparatus.
D) secretory vesicles are not fusing with the plasma membrane.
E) all of the above

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protein possesses a signal for localization within the Golgi apparatus.

Question: Which one of the following proteins would be least likely to pass through a Golgi apparatus?
A: Ribosomal proteins
B: Lysosomal enzymes
C: Cell surface proteins
D: Secreted proteins
E: ER proteins

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ribosomal proteins

Question: Lysosomal proteins are marked by adding a phosphate to a(n) _______ group.
Lysosomal proteins are marked by adding a phosphate to a ____________
A: glucose
B: serine
C: GDP
D: mannose

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mannose

Question: Lysosomal proteins are initially incorporated into _______ vesicles.
lysosomal proteins are initially incorporated into _______ vesicles.
A: a. uncoated
B: clathrin-coated
C: COPI-coated
D: COPII-coated

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clathrin-coated

Question: Which one of the following cellular processes is most likely to happen in the Golgi?
A: Synthesis of membrane phospholipids
B: Synthesis of ceramide
C: Synthesis of sphingomyelin
D: Translation on membrane bound ribosomes
E: N-linked glycosylation

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Synthesis of sphingomyelin

Question: The cis-Golgi:
A: prevents the retrograde transfer of proteins from the Golgi to the RER.
B: is the cellular location where stop transfer sequences are attached to transmembrane proteins.
C: is the portion of the Golgi apparatus from which fully modified proteins are directed to their final destinations.
D: is physically continuous with the trans-Golgi.
E: is the portion of the Golgi apparatus closest to the RER and nucleus.

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is the portion of the Golgi apparatus closest to the RER and nucleus.

Question: Why does a lysosome not degrade itself? Choose all that apply.
A: The lumenal surface of a lysosomal membrane contains a thick layer of carbohydrate, and there are no enzymes in a lysosome that hydrolyze carbohydrates.
B: The membrane of a lysosome is synthesized with special phospholipids that are more resistant to hydrolysis.
C: Mannose-6-phosphate provides a special signal that prevents acid hydrolases from catalyzing their respective reactions in the presence of that signal.
D: Although it is known that lysosomes do not degrade themselves, it remains a mystery as to why they are protected from their own hydrolases.
E: None of the above. Lysosomes do in fact degrade themselves eventually.

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None of the above. Lysosomes do in fact degrade themselves eventually.

Question: Lysosomes that lack mannose-6-phosphate receptors _____.
Lysosomes that lack mannose-6-phosphate receptors _____.
A: have unstable membranes
B: receive "modified" enzymes and are thus unable to break down carbohydrates
C: do not receive enzyme shipments from the Golgi apparatus
D: stick to transport vesicles and impede the transfer of enzymes

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do not receive enzyme shipments from the Golgi apparatus

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