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Cytoskeleton

Course Name:  Cell Biology
Course No.308
Teacher:  Dr. Steven P. Berg
Teacher's Home Page:  http://bio.winona.msus.edu/berg/fac_sb.htm
Teacher's Email:  sberg@vax2.winona.msus.edu

Student Name:    
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No. of Questions= 20


1.  Which of the following IS NOT one of the major cytoskeletal elements?
a) microtubules
b) intermediate filaments
c) myosin
d) microfilaments
2.  What technique has been employed to study the cell shown below?
a) Phase contrast microscopy
b) Electron microscopy
c) Immunofluorescence microscopy
d) Scanning electron microscopy
3.  How were the three distinct structural elements of the cytoskeleton discovered?
a) Biochemistry.
b) Electron microscopy.
c) Fluorescence microscopy.
d) Light microscopy.
4.  You have a hollow cylinder composed of two slightly different globular proteins. The outer dimension is 25 nm and the inner dimension is 15 nm. What do you have?
a) A microtubule.
b) A microfilament.
c) An intermediate filament.
5.  You have a long assembly of a single globular protein which is several hundred nm long and 7 nm wide. What do you have?
a) A microtubule.
b) A microfilament.
c) An intermediate filament.
6.  What additional molecule must be available for G-actin to polymerize into F-actin?
a) ATP
b) GTP
c) tubulin (alpha and beta forms)
d) myosin
7.  What is the relationship between actin and myosin?
a) Actin binds to myosin.
b) The globular portion of myosin binds to F-actin.
c) Myosin is needed for actin polymerization.
8.  Which type of cytoskeletal structure is most variable depending on tissue type?
a) Microtubules
b) Microfilaments
c) Intermediate filaments
9.  You have an assembly of polymerized protein, the monomer of which has a central rodlike domain flanked by N-terminal and C-terminal domains. What is this assembly.
a) A microtubule.
b) A microfilament.
c) An intermediate filament.
10.  The keratin loops that pass through desmosomes, thus tightly connecting adjacent cells are what type of cytoskeletal element?
a) Microtubules.
b) Microfilaments.
c) Intermediate filaments.
11.  Intestinal microvilli are filled with what type of structural element?
a) Microtubules
b) Microfilaments
c) Intermediate filaments
12.  What is the function of the many actin-binding proteins found in the cell?
a) Actin binding proteins serve as crosslinking proteins.
b) Actin binding proteins serve as motor proteins.
c) Actin-binding proteins regulate the assembly and function of actin.
13.  What are Motor MAPs?
a) Motor MAPs are organelles which bind to microfilaments and hence produce a structure which can induce motion.
b) Motor MAPs (eg: kinesin and dynein) bind to Mts and use the energy in ATP to drive directional motion.
c) Motor MAPs (eg: myosin) bind to actin and cause the decrease in length of the actin/myosin filaments.
14.  What is the function of nonmotor MAPs?
a) Nonmotor MAPs control MT organization in the cytoplasm of the cell.
b) Nonmotor MAPs bind to Mts and help produce motion.
c) Nonmotor MAPs bind to microfilaments and produce motion.
15.  Which cytoskeletal element is illustrated in the diagram below?
a) Microtubule
b) Microfilament
c) Intermediate filament
16.  Which cytoskeletal element is illustrated below? (The two colors are used only to accent the spiraling behavior.)
a) Microtubules
b) Microfilaments
c) Intermediate filaments
17.  What cytoskeletal structure does the protein below bind to?
     
a) MTs
b) MFs
c) IFs
18.  What important property is illustrated in the cartoon below?
a) Microtubules have a + end and a - end.
b) Myosin filaments have polarity.
c) There is inherent polarity in the filament produced when actin monomers assemble into filamentous actin.
d) Many proteins are able to recognize either the + end or the - end of the microtubule and orient themselves in the cell.
19.  What important property is illustrated by the cartoon below?
a) Only G-actin with bound ATP can assemble into a microfilament.
b) Actin-ATP forms a cap on one end of the microfilament.
c) Under conditions where the rate of assembly = the rate of disassembly, the length of the filament remains constant.
d) Under conditions where the rate of assembly = the rate of ATP hydrolysis, the size of the ATP cap is constant.
e) All of the other statements are properties illustrated by the animation.
20.  What important property of microfilaments is illustrated in the animation below?
a) Microfilament assembly requires ATP.
b) Microfilaments treadmill.
c) There are three types of G-actin which assemble into microfilaments.



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