Functions Of Cytoskeletal Elements
WHO THE HELL CAARESS/!?
- 1.In a pulse-chase procedure, if the chase is longer, whichstatement below correctly describes the location of theradioactively labeled proteins in the cell?
- A.
Closer to the synthesis site
- B.
Farther from the nucleus
- C.
Farther from the synthesis site
- D.
Closer to the nucleus
- E.
Farther from the mitochondria
- 2.You incubate liposomes with a series of purified proteinsnormally found in the coats of cell transport vesicles. Afteradding one of them to the liposome mixture, budding ofvesicles from the liposomes began. What does thismean?
- A.
Liposomes cause the protein to denature
- B.
The protein is involved in the initiation of vesicle formation.
- C.
The protein is involved in liposome denaturation
- D.
The protein triggers protein synthesis.
- E.
The protein causes the entry of water into the liposomes
- 3.How and where is the asymmetry of the phospholipidbilayers initially established?
- A.
It is initially established in the Golgi complex during lipid and protein modification
- B.
It is initially established in the ER during lipid and protein synthesis.
- C.
It is initially established in the secretory vesicles during lipid and protein modification
- D.
It is initially established in the mitochondria by random insertion into the membranes.
- E.
All of the above
- 4.Which type of cytoskeletal element is described as a solid,thinner structure, often organized into a branchingnetwork, and composed of actin subunits?
- A.
Microfilaments
- B.
Microtubules
- C.
Intermediate filaments
- D.
All of the above
- E.
Macrofilaments
- 5.Which of the following is (are) made on free ribosomes?
- A.
Proteins that are to remain in the cytosol
- B.
Peripheral proteins of the inner cell membrane surface
- C.
Peripheral proteins of the outer cell membrane surface
- D.
Proteins to be transported to the nucleus
- E.
A, b and d
- 6.Which molecule below is a GTP-binding protein that isrequired for the release of a clathrin-coated vesicle fromthe membrane on which it was formed?
- A.
AP2
- B.
GGA
- C.
Clathrin
- D.
Dynamin
- E.
Opsonin
- 7.Which endosome serves as a sorting station that directsdifferent types of receptors and ligands along differentpathways?
- A.
Medial endosomes
- B.
Late endosomes
- C.
Early lysosomes
- D.
Medial lysosomes
- E.
Early endosomes
- 8.What determines the sequence of sugar addition toglycoproteins traveling through the Golgi complex?
- A.
Nothing - the sequence is random
- B.
The spatial arrangement of specific glycosyltransferases that contact proteins as they pass through the Golgi complex
- C.
The concentration of sugars in the Golgi complex
- D.
The sequence of sugars in the Golgi complex
- 9.Which model of Golgi complex formation suggests that thecisternae of a Golgi stack remain in place as stablecompartments held together by a protein scaffold while thecargo is shuttled through the Golgi via vesicles that budfrom one compartment and fuse with a neighboring one?
- A.
The cisternal maturation model
- B.
The cargo carrying model
- C.
The vesicular transport model
- D.
The secretory transport model
- E.
The chemiosmotic model
- 10.Why is the ER so well-suited and ideally constructed for itsrole as a port of entry for secretory proteins?
- A.
It has a large surface area allowing the attachment of many ribosomes
- B.
The ER cisternae lumen favors the folding and assembly of proteins.
- C.
The RER segregates secretory, lysosomal and plantcell vacuolar proteins from other newly made proteins, allowing their modification, and sends them to their destination.
- D.
A and c
- E.
A, b and c
- 11.A small subfamily of kinesins moves toward the minus end of amicrotubule, while the rest move toward the plus end. Whenthe neck and stalk of a minus-directed kinesin is joined to thehead of a plus-directed kinesin, in what direction will
- A.
In a retrograde direction
- B.
Toward the plus-end of the microtubule
- C.
In an anterograde direction
- D.
Towards the fastest growing end of the microtubule
- E.
C and d
- 12.The heads of kinesin-like proteins have fairly closely relatedamino acid sequences but diverse tail sequences. What isthe explanation for this seeming contradiction?
- A.
The similarity of kinesin-like protein heads and the variation in their tails are purely random.
- B.
The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind.
- C.
The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind.
- D.
The similarity of the heads is explained by their similar roles in interacting with microtubules; the variation in the tails reflects the similar cargoes to which they bind
- E.
The similarity of the heads is explained by their different roles in interacting with microtubules; the variation in the tails reflects the variety of cargoes to which they bind
- 13.Which type of cytoskeletal element is characterized as ahollow, rigid cylindrical tube with walls composed of tubulinsubunits
- A.
Microfilments
- B.
Microtubules
- C.
Intermediate filaments
- D.
All of the above
- 14.The vesicle is targeted to the appropiate compartment by_________.
- A.
Endocytosis
- B.
Rabs
- C.
GTP binding proteins
- D.
T-snares
- 15.Most vesicles budding from the Golgi body have a fuzzy,electron-dense coat on their ______ surface. The coatappears to be made of _______.
- A.
Luminal, lipid
- B.
Cytosolic, lipid
- C.
Cytosolic, carbohydrate
- D.
Luminal,protein
- E.
Cytosolic, protein
- 16.The uptake (both specific and nonspecific) of fluid,dissolved solutes and suspended macromolecules iscalled ________.
- A.
Endocytosis
- B.
Phagocytosis
- C.
Autophagy
- D.
Exocytosis
- E.
Pinocytosis
- 17.What recognizes the signal sequence as it exits theribosome and of what is it made?
- A.
Signal recognition particle, DNA and protein
- B.
Signal recognition particle, carbohydrate and protein
- C.
SRP and its components, RNA and protein.
- D.
SRP and its components, RNA and protein.
- E.
Signal recognition protein, carbohydrate and lipid
- 18.In addition to microtubule motor proteins, ________ arealso involved in vesicular transport.
- A.
Actin
- B.
Myosins
- C.
Tubulin
- D.
Dynein
- E.
Kinesin-like proteins
- 19.All of the following statements about cellular trafficking aretrue EXCEPT
- A.
COPI-coated vesicles move materials from Golgi to the secretory vesicle
- B.
Tethering proteins mediate docking between target and vesicle
- C.
COPII-coated vesicles move materials from ER to Golgi
- D.
Movement may be mediated by microtubules
- 20.The accumulation of misfolded proteins in the ER is a potentially lethal situation and thus causes the triggering ofwhat process?
- A.
The polysomal response
- B.
The posttranscriptional response
- C.
The unfolded protein response (UPR)
- D.
The proteasomal response
- 21.How do protein coats select the contents of the vesiclesthey help to form?
- A.
They electromagnetically attract the correct cargo proteins.
- B.
The coats have a specific affinity for the cytosolic tails of integral membrane receptors for cargo proteins that reside in the donor membrane.
- C.
The coats have a specific affinity for the luminal tails of integral membrane
- D.
Receptors for cargo proteins that reside in the donor membrane.
- E.
The coat proteins directly attach to the cargo proteins in the lumen of the forming vesicles.
- 22.Kinesin movement along a microtubule is said to be________ meaning that it can move long distances alongan individual microtubule without falling off
- A.
Excessive
- B.
Progressive
- C.
Excessive
- D.
Processive
- E.
Aggressive
- 23.What is the supposed function of the small subfamily ofkinesins that is incapable of movement
- A.
They stabilize microtubules
- B.
They encourage depolymerization
- C.
They cause polymerization.
- D.
They block other kinesins from moving along microtubules.
- E.
They add phosphate groups to tubulin
- 24.Typically, receptors for hormones or growth factors aredestroyed during endocytosis, leading to a reduction in thecell’s sensitivity to further stimulation by that particularhormone or growth factor. This is a mechanism by whichcells regulate their ability to respond to extracellular messengers. What is it called?
- A.
Receptor up-regulation
- B.
Receptor annihilation
- C.
Endocytic assignation
- D.
Receptor down-regulation
- E.
Super signaling
- 25.Which of the proteins below is(are) not made on themembrane-bound ribosomes of the RER?
- A.
Inner peripheral membrane proteins
- B.
Soluble lysosomal proteins
- C.
Vacuolar enzymes
- D.
Proteins of the extracellular matrix
- E.
All of the above
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