CELL BIOLOGY – EXAM 3 PRACTICE TEST (200 QUESTIONS) – MOST TESTED QUESTIONS FOR UNIVERSITY BIOLOGY

CELL BIOLOGY – EXAM 3 PRACTICE TEST (200 QUESTIONS) – MOST
TESTED QUESTIONS FOR UNIVERSITY BIOLOGY
Which of the following is NOT a structure comprised mostly of actin filaments?

a) stress fiber

b) primary cilium

c) lamellipodium

d) contractile ring

e) microvilli - ANSWER****b) primary cilium



Which of the following actin binding proteins is capable of nucleating the formation of new
actin filaments?

a) filamin

b) fimbrin

c) formin

d) fibrin

e) none of the above are capable of nucleating the formation of new actin filaments. -
ANSWER****c) formin


Which of the following events "cocks" the neck linker on myosin II motor proteins?

a) ATP binding to the motor head

b) ATP hydrolysis

c) binding of the motor head to an actin filament

d) dissociation of inorganic phosphate from the motor head

e) dissociation of the ADP from the motor head - ANSWER****b) ATP hydrolysis



Which of the following events triggers the "power stroke" for myosin II motor proteins?

,1. Dissociation of Pi

2. ATP binding

3. ATP hydrolysis

4. Exchange of ADP to ATP - ANSWER****1. Dissociation of Pi



In a motile keratocyte, where would you expect to find most of the ARP 2/3 complex?



a. Trailing edge

b. Leading edge

c. Near stress fibers

d. Near centrosome - ANSWER****b. Leading edge



Which protein is the Calcium sensor that triggers contraction in the sarcomere?



a. Tropomodulin

b. Troponin

c. Tropomyosin

d. Trampolinin - ANSWER****b. Troponin



Wave-like movement of eukaryotic flagella? - ANSWER****Dynein



When does catastrophe occur? - ANSWER****when the microtubules lose its GTP cap



Monomeric G-protein that regulates actin cytoskeleton - ANSWER****Rho

,All myosins move toward the (+) end of actin filaments



True or False - ANSWER****True



- minus end capping protein in the sarcomere - ANSWER****Tropomodulin



+ plus end capping protein in the sarcomere - ANSWER****CapZ



Which of the following proteins severs actin filaments in the lamellipodia



a. Deformin

b. Profilin

c. Cofilin

d. Formin - ANSWER****Cofilin



Which of the following events propels the lamellipodium of a motile cell forward?

a) kinesin motor proteins

b) myosin motor proteins

c) ATP hydrolysis

d) actin polymerization

e) microtubule polymerization - ANSWER****d) actin polymerization



In a motile cell, where would you expect to find most of the ARP complex?

a) at the leading edge of the cell

, b) at the trailing edge of the cell

c) bound to the endoplasmic reticulum

d) in the cortex of the cell

e) in all of the above - ANSWER****a) at the leading edge of the cell



Which of the following proteins promotes the depolymerization of actin filaments

a) troponin

b) severin

c) depolymin

d) profilin

e) cofilin - ANSWER****e) cofilin



Which of the following fungal products binds to and stabilizes actin filaments?

a) phalloidin

b) cytochalasin

c) swinholide

d) latrunculin

e) taxol - ANSWER****a) phalloidin



Is the following statement TRUE or FALSE? "Lamellipodia are autonomous motile structures
driven by actin polymerization."

a) The statement is TRUE

b) The statement is FALSE - ANSWER****a) The statement is TRUE



Which of the following monomeric G-proteins is involved in remodeling of the actin
cytoskeleton?