Exam 3 Practice Problems

In an experiment, you treated cells with a drug that blocks ATP synthesis, which of the following processes will NOT be arrested immediately? a. microtubule assembly b. exocytosis c. actin filament assembly d. cell migration

a

Which of the following is NOT directly required for the function of synapse? a. H+ pump b. Synaptic vesicle c. SNARE d. voltage gated Ca2+ channel

a

Which of the following statements is TRUE? a. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell. b. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol. c. A receptor bound by only one type of signal molecule can mediate only one kind of cell response. d. Each type of receptor must induce an independent signaling pathway and avoid interference with other intracellular signaling pathways.

a

Which of the following statements is FALSE? a. Most G-protein-coupled receptors are multipass transmembrane proteins with 7 α-helixes. b. Activated G protein produces 3 separate subunits that function independently. c.Each calmodulin can bind to 4 calcium ions. d. Receptor tyrosine kinases (RTK) always form dimers after binding with signal molecules.

b

Which statement about synapse is TRUE? a. Neurotransmitters are released by the presynaptic cell and absorbed by the postsynaptic cell. b. One neuronal cell can be attached by many synapses. c. The presynaptic cell and postsynaptic cell are connected by tight junctions. d. Synapse is a specific structure that only mediates signal transduction between neuronal cells.

b

To study the function of keratin, which of the following models can be chosen? a. yeast b. drosophilia c. zebra fish d. mouse e. b, c & d f. c & d g. all of them

f

To study the function of lamin, which of the following models can be chosen? a. yeast b. drosophilia c. zebra fish d. mouse e. b, c & d f. c & d g. all of them

g

To design a drug that can inhibit cell migration, which protein may NOT be chosen as the target? a. actin b. ARP c. kinesin d. myosin e. integrin

c

To design a drug that can inhibit insulin secretion, which protein should NOT be chosen as a target? a. tubulin b. kinesin c. dynein d. clathrin

c

Which of the following happens when a G-protein-coupled receptor activates a G protein? a. The β subunit exchanges its bound GDP for GTP. b. The GDP bound to the α subunit is phosphorylated to form bound GTP. c. The α subunit exchanges its bound GDP for GTP. d. It activates the α subunit and inactivates the βγ complex.

c

Which of the following neurotoxins directly blocks the acetylcholine receptor? a. VX b. Botulinum Toxin c. Curare d. Tetrodotoxin

c

You want to design a drug to inhibit neuron transduction in brain. Which of the following protein complexes can NOT be a target? a. Ca2+ pump b. K+ leak channel c. mechanical-gated cation channel d. voltage-gated Na+ channel

c

Cell movement involves the coordination of many events in the cell. Which of the following phenomena is NOT required for cell motility? a. Nucleation of new actin filaments. b. Integrin association with the extracellular environment. c. Myosin-mediated contraction at the rear of the moving cell. d. Influx of Ca2+ into cytoplasm.

d

During the action potential propagation on neuron cell, which of the following best describes the voltage changes in one plasma membrane region? a. 0 mV > +40 mV > +60 mV > +40 mV > 0 mV b. -40 mV > 0 mV > +40 mV > -40 mV c. -60 mV > -40 mV > 0 mV > -40 mV > -60 mV d. -60 mV > -40 mV > 0 mV > +40 mV > -60 mV

d

Researchers studying vesicular transport assembled several transport components in vitro (in a test tube). They set up the microtubules, then added vesicles and kinesin. When they put everything together, there was no movement of transport vesicles along microtubule. What were they missing? a. Ca2+ b. GTP c. SNARE d. ATP

d

Which of the following compounds can NOT be a potential anti-cancer drug? a. a compound that blocks association of Ras-GEF with RTK b. a compound that inhibits Ras-GEF c. a compound that activates Ras-GAP d. a compound that inhibits Ras-GAP e. a compound that inhibits MAPKKK

d

Which of the following mutations would lead to an excess in the amount of glucose in skeletal muscle cells? a. a GPCR mutant form that loses the binding activity to adrenaline b. A G-protein mutant that loses GTP-binding ability c. A PKA mutant form that loses cAMP-binding ability d. A PKA mutant form in which the inhibitory subunits lose the binding ability to the kinase subunits

d

Which of the following would you expect to see in a cell that has been exposed to colchicine? a. Inability to regulate cell size b. An increased synthesis of cellular proteins c. Disappearance of the nucleus d. Failure of the cell to divide

d

Acetylcholine controls the contraction of skeleton muscle and smooth muscle using different signaling pathways. Which mechanism is shared by these two pathways? a. Acetylcholine binds to ion-channel receptor b. Ca2+ release from sarcoplasmic reticulum c. Ca2+ activates calmodulin d.Phosphorylation of myosin

b

At death, the muscles of the body become very still and inextensibile (rigor mortis). What happens in the contractile cycle? a. the myosin head is released from actin and cannot rebind b. the myosin head is attached to the actin and cannot release c. the myosin head is bound to ADP and cannot bind actin d. the myosin head is bound to ATP and cannot bind actin

b

During a drug screen you find a compound that can block the binding of Ca2+ to troponin. Predict the effect of this drug. a. muscle spasm b. muscle paralysis c. hypnosis d. no effect

b

To design a drug that can inhibit LDL uptake which protein should NOT be chosen as the target? a. tubulin b. kinesin c. dynein d. clathrin

b

Which of the following compounds can be a potential anti-cancer drug? a. A compound that activates Ras-GEF b. A compound that activates Ras-GAP c. A compound that activates MAPKK d. A compound that activates mTOR

b

Which of the following proteins can move cargos through an actin filament? a. kinesin b. myosin c. filamin d. dynein

b

Which of the following statements about the cytoskeleton is FALSE? a. The cytoskeleton controls the location of organelles in eukaryotic cells. b. Covalent bonds between protein monomers hold together cytoskeletal filaments. c. The cytoskeleton is made up of three types of protein filaments. d. The cytoskeleton of a cell can change in response to signals.

b