Activation of which of the following is associated with the formation of focal a

Question

Activation of which of the following is associated with the formation of focal adhesions and stress fibers?

A) Rho B) Ras C) Cdk-42 D) intermediate filaments E) ?-tubulin

Which of the following drugs disrupt microtubules and can used for chemotherapy?

A) cytochalasin D   B) vincristine   C) tubulin   D) latrunculin A   E) Phallodin

Rho GTPases have the all of the following effects on cytoskeletal actin except

A) stress fiber formation.B) formation of pseudopodia. C) stabilization of neurons. D) assembly of the cytokinetic furrow. E) regulation of endocytosis and exocytosis.

Which of the following about the current model of muscle contraction is correct ?

A) myosin binds calcium. B) titin binds calcium. C) actin has ATPase activity. D)

myosin has ATPase activity. E) actin and myosin have the same molecular

weight.

Which of the following major protein components of skeletal muscle is incorrectly matched with its function?

A) titin-links thick filaments at Z line B) nebulin-links thin filaments at Z line C)

myomesin-myosin binding protein present at M line

D) troponin-binds along the length of the thin filaments and covers myosin binding sites E) actin-major component of thin filaments

All of the following are moved by molecular motors except

A) secretory vesicles.

B) cytoskeletal filaments.

C) the Golgi complex.

D) glucose.

E) chloroplasts.

Striated muscle has light and dark bands. The light bands are called ________, whereas the dark bands are called ________.

A) Z lines; M lines B) H zones; M zones

C) A bands; I bands D) I bands; A bands E) M lines; A bands

In relaxed muscle, calcium is found in high concentration in the

A) myofibril. B) T tubules.

C) sacroplasmic reticulum. SR D) sarcolemma. E) neuromuscular junction.

All of the following are actin-dependent nonmuscle motility except

A) translocation of multienzyme complexes.

B) pinching off of the cleavage furrow in cytokinesis. C) chemotaxis.

D) cyclosis or cytoplasmic streaming. E) amoeboid movement.

Calcium-calmodulin complexes ultimately mediate the phosphorylation of myosin in which of the following cells?

A) smooth muscle B) cardiac muscle

C) neurons D) pacemaker E) skeletal muscle

In addition to microtubule motor proteins, ________ are also involved in vesicular transport.

A) nonmuscle myosins B) actin C) tubulin D) leptin E) dyesins

The calcium pump or calcium ATPase in skeletal muscles

A) is responsible for removing calcium from the T tubule.

B) increases the level of calcium in the axon terminal.

C) does not need energy to operate.

D) removes calcium from the sarcoplasm and pump it back to the sacroplasmic reticulum

E) increases bone density.

Muscle contraction occurs in a cyclic process. Which of the following sequences is in the correct order?

A) power stroke, cross bridge formation, cross bridge dissociation, cocking of myosin

B) cross bridge formation, power stroke, cross bridge dissociation, cocking of myosin

C) cross bridge formation, cocking of myosin, power stroke, cross bridge dissociation

D) cross bridge formation, cross bridge dissociation, cocking of myosin, power stroke

E) cross bridge formation, power stroke, cross bridge dissociation, power stroke, cocking of myosin

Which of the following process(es) requires energy in the form of ATP hydrolysis ?

A) power strokeB) cross bridge formation

C) cocking of myosinD) cross bridge dissociationE) all of the above

Dyneins are

A) proteins associated with intermediate filament.

B) associated with cilia and flagella. C) monomeric myosin-like proteins.

D) responsible for anterograde transport. E) all of the above

Which of the following is associated with retrograde movement in fast axonal transport?

A) dynein B) actin C) tubulin D) myosin E) kinesin

Kinesin is a motor molecule that is characterized by

A) activation of sliding in flagellar microtubules. B) sliding along actin in sarcomere.

C) motion toward the "plus" end of the microtubule. D) motion along actin filaments. E) motion toward the "minus" end of the microtubule.

All of the following are examples of nonmuscle motility and contractility except

A) microsome formation. B) pseudopodia formation. C) cytoplasmic streaming. D) actin polymerization of Listeria. E) phagocytosis.

You wish to inhibit the contraction of muscle in vitro as a control for an experiment you are conducting. To do this, which of the following would you use?

A) colchicine B) ATPase inhibitors C) vinblastin   D) taxol E) serotonin

A calcium-binding protein that aids in the activation of many enzymes, including myosin light-chain kinase, is

A) calcium phosphorylase. B) activase. C) calmodulin. D) myosin light-chain phosphatase. E) junctional complex.

Explanation / Answer

1) Rho

2) vincristine

3) formation of pseudopodia

4) actin has ATPase activity

5) troponin-binds along the length of the thin filaments and covers myosin binding sites

6) chloroplasts

7) I bands; A bands

8) sacroplasmic reticulum

9) chemotaxis.

10) smooth muscle

11) nonmuscle myosins

12) removes calcium from the sarcoplasm and pump it back to the sacroplasmic reticulum

13) cross bridge formation, power stroke, cross bridge dissociation, cocking of myosin

14) cross bridge formation

15) all of the above

16) dynein

17) motion toward the "plus" end of the microtubule

18) actin polymerization of Listeria

19) ATPase inhibitors

20) calmodulin

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