Cell Biology Exam 3

Which of the following statements is FALSE? A. Most G-protein-coupled receptors are multiphase 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. Activated G protein produces 3 separate subunits that function independently

Which of the following statements is TRUE for Notch signaling? A. Delta is a paracrine ligand that binds to Notch receptor locally B. Ca2+ release from sarcoplasmic reticulum C. To silence the signaling, the nuclear Notch fragment shuttles back to the plasma membrane D. The Delta-Notch complex enters nucleus and functions as transcription factor

B. Ca2+ release from sarcoplasmic reticulum

Which of the following statements is TRUE? A. All cells will respond to the endocrine signals as endocrine molecules are broadcast throughout the body. B. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell C. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol D. A receptor bound by one type of signal molecule mediates only One kind of cell response E. Each type of receptor induces an independent signaling pathway and avoids interference with other intracellular signaling pathways

B. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell

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. Kinesin

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. Muscle paralysis

To design a drug that can inhibit insulin secretion, which protein should NOT be chosen as the target? A. Tubulin B. Kinesin C. Dynein D. Clathrin

C. Dynein

To design a drug that can inhibit cancer cell migration, which protein may NOT be chosen as the target? A. Actin B. ARP C. Kinesin D. Myosin E. Integrin

C. Kinesin

Which of the following proteins can move cargos through an actin filament? A. Filamin B. Kinesin C. Myosin D. Dynein

C. Myosin

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. The α subunit exchanges its bound GDP for GTP

Which of the statements below about intermediate filaments is TRUE? A. They are made of globular subunits. B. They can be found in the cytoplasm and the nucleus of all eukaryotic cells C. They can be anchored to the plasma membrane at a type of cell-cell junction D. They are strength filaments with about 25 nm in diameter

C. They can be anchored to the plasma membrane at a type of cell-cell junction

Which of the following is NOT one of the pathways activated by RTKs? A. RAS-MAPK B. Bad-Bcl2 C. cAMP-PKA D. Akt-Tor

C. cAMP-PKA

Which of the following compound 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 inhibits Ras-GAP D.A compound that inhibits MAPKKK

C.A compound that inhibits Ras-GAP

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

Researchers studying vesicular transport assembled several transport components in vitro (in a test tube). They set up the stabilized 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. GTP B. SNARE C. Ca2+ D. ATP

D. ATP

Which of the following mutations may suppress cell proliferation? A. A mutation on APC complex that prevents its binding with β-catenin B. A mutation on APC complex that permanently inactivate its function C. A mutation in the NLS (nuclear localization signal sequence) of β-catenin D. All of them

D. All of them

To study the function of keratin which of the following models can be chosen? A. Yeast B. Drosophila C. Zebra Fish D. Mouse E. B, C, and D F. C and D G. All of them

F. C and D

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

A. Influx of Ca2+ into cytoplasm

Which of the following would you expect to see in a cell that has been exposed to colchicine? A. Mis-organized endomembrane system B. Disappearance of the nucleus C. An increased synthesis of cellular proteins D. Inability to regulate cell size

A. Mis-organized endomembrane system

Which is in the correct order (to upstream to downstream) A. X-Ras-Y B. Y-Ras-X C. X-Y-Ras D. Ras-X-Y E. Y-X-Ras F. Ras-Y-X

A. X-Ras-Y (upstream-Ras-downstream)

The members of the steroid hormone receptor family ____________ A. interact with signal molecules that diffuse through the plasma membrane B. are cell-surface receptors C. function as monomers D. are found only in the nucleus

A. interact with signal molecules that diffuse through the plasma membrane

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. A compound that activates Ras-GAP

To study the function of lamin which of the following models can be chosen? A. Yeast B. Drosophila C. Zebra Fish D. Mouse E. B, C, and D F. C and D G. All of them

G. All of them

In an experiment, you treated cells with a drug that blocks ATP synthesis, which of the following processes will be arrested immediately? A. Microtubule assembly B. Exocytosis C. Actin filament assembly D. Cell Migration E. A,B F. C,D G. B,C,D

G. B,C,D

You want to design a drug that can relax both skeletal and smooth muscles. Which of the following proteins could be a target? A. Voltage gated Na+ channel B. Voltage gate Ca++ channel C. Ca++ pump D. Troponin E. Calmodulin F. B & C G. A,B,C H. A & B I. All of them

H. A & B