cell bio E3

Which of the following statements about the unfolded protein response (UPR) is FALSE? Activation of the UPR results in the cytoplasmic activation of gene regulatory proteins. Activation of the UPR results in the production of more ER membrane. Activation of the UPR occurs when receptors in the cytoplasm sense misfolded proteins. Activation of the UPR results in the production of more chaperone proteins.

Activation of the UPR occurs when receptors in the cytoplasm sense misfolded proteins.

Which of the following conditions is likely to decrease the likelihood of skeletal muscle contraction? Addition of a drug that blocks Ca2+ binding to troponin. An increase in the amount of ATP in the cell. Partial depolarization of the traverse T-tubule membrane, such that the resting potential is closer to zero. A mutation in tropomyosin that decreases its affinity for the actin filament.

Addition of a drug that blocks Ca2+ binding to troponin.

During which stage of mitosis do the sister chromatids separate and get pulled to opposite poles of the cell? Prometaphase Metaphase Telophase Anaphase Prophase

Anaphase

Apoptosis differs from necrosis in that necrosis _____. Requires the reception of an extracellular signal. Causes cells to swell and burst, whereas apoptotic cells shrink and condense. Causes DNA to fragment. Involves a caspase cascade.

Causes cells to swell and burst, whereas apoptotic cells shrink and condense.

You observe cells under a microscope undergoing mitosis. The sister chromatids have condsensed, but they are not paired up. The cell is in Prometaphase. This is likely due to a defect in which protein? cohesin Cdc25 condensin tubulin

Cohesin

During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in __________ signaling. endocrine contact-dependent neuronal paracrine

Contact dependent

Cell cycle progression is controlled by Cdk-cyclin activity. All of the following are methods to regulate Cdk-cyclin activity EXCEPT. Ubiquitination of the cyclin by APC. Synthesis of the cyclin component . Inhibitory phosphates Degradation of the cyclin by separase

Degradation of the cyclin by separase

Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels? lysosome → endosome → plasma membrane Golgi → lysosome → plasma membrane ER → Golgi → plasma membrane ER → lysosome → plasma membrane

ER → Golgi → plasma membrane

In flagella, microtubules are arranged in a 7+2 pattern. True False

False

Lamellipodia are long, thin, actin-containing extensions. True False

False

When a signal needs to be sent out to most cells throughout a multicellular organism, the signal most suited for this is ________ scaffold hormone dissolved gas neurotransmitter

Hormone

Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed below. Which of the following statements is FALSE? In the absence of a survival signal, Bad is phosphorylated. In the presence of a survival signal, the cell-death inhibitory protein Bcl2 is active. In the presence of a survival signal, Akt is phosphorylated. In the absence of a survival signal, Bad inhibits the cell-death inhibitor protein Bcl2.

In the absence of a survival signal, Bad inhibits the cell-death inhibitor protein Bcl2.

What is the role of the nuclear localization sequence in a nuclear protein? It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore. It is a hydrophobic sequence that enables the protein to enter the nuclear membranes. It prevents the protein from diffusing out of the nucleus through nuclear pores. It aids in protein unfolding so that the protein can thread through nuclear pores.

It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

How does S-Cdk help guarantee that replication occurs only once during each cell cycle? It phosphorylates the Cdc6 protein, marking it for destruction. It promotes the assembly of a prereplicative complex. It phosphorylates and inactivates DNA helicase. It blocks the rise of Cdc6 concentration early in G1.

It phosphorylates the Cdc6 protein, marking it for destruction.

The motor protein _____ transports cargo to the inward (-) end of microtubules.

Kinesin

In the laboratory, you mutate a gene in neurons and discover that the resulting cells are unable to transport vesicles and organelles to the axon terminal, but they can still transport vesicles and organelles from the axon terminal to the cell body. The gene you mutated is most likely a _________. myosin motor protein. dynein motor protein. kinesin motor protein. spectrin motor protein.

Kinesin motor protein

During which stage of mitosis does mitotic spindle begin to form? Anaphase Telophase Metaphase Prometaphase Prophase

Prophase

Which of the following statements is TRUE? Proteins destined for the ER are translated by cytosolic ribosomes and are targeted to the ER when a signal sequence emerges during translation. Proteins destined for the ER translocate their associated mRNAs into the ER lumen where they are translated. Proteins destined for the ER are translated by a special pool of ribosomes whose subunits are always associated with the outer ER membrane. Proteins destined for the ER are translated by a pool of cytosolic ribosomes that contain ER-targeting sequences that interact with ER-associated protein translocators.

Proteins destined for the ER are translated by cytosolic ribosomes and are targeted to the ER when a signal sequence emerges during translation.

Which family of GTPases control the organization of the actin cytoskeleton? Ras Rab Ran Rho

Rho

When does DNA replication occur? Prophase Prometaphase S phase G1 phase

S phase

DNA damage is present during the G1 stage of interphase. All of the following are possible outcomes EXCEPT. Cell cycle is paused while DNA repair take place. The cell undergoes apoptosis. The cell immediately enters S phase. Cell cycle progression is stopped.

The cell immeaditely enters S phase

Which of the following statements about transport into mitochondria is FALSE? Proteins that are transported into these organelles are unfolded as they are being transported. The signal sequence is removed once the protein has been imported into these organelles. The protein moves completely through the protein translocator in the outer membrane, then the protein diffuses in the lumen until it encounters a protein translocator in the inner membrane. The signal sequence on proteins destined for these organelles is recognized by a receptor protein in the outer membrane of these organelles.

The protein moves completely through the protein translocator in the outer membrane, then the protein diffuses in the lumen until it encounters a protein translocator in the inner membrane.

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

The α subunit exchanges its bound GDP for GTP.

During treadmilling, when actin monomers are removed as they are added, GTP is hydrolyzed to GDP. True False

True

Which of the following protein families are NOT involved in directing transport vesicles to the target membrane? Rabs adaptins tethering proteins SNAREs

adaptins

The figure below shows how normal signaling works with a Ras protein acting downstream of an RTK. You examine a cell line with a constitutively active (always ON) Ras protein that is always signaling. Which of the following conditions will turn off signaling in this cell line? addition of a drug that blocks protein Y from interacting with its target addition of a drug that prevents protein X from activating Ras addition of a drug that increases the affinity of protein Y and Ras addition of a drug that increases the activity of protein Y

addition of a drug that blocks protein Y from interacting with its target

The hydrolysis of GTP to GDP carried out by tubulin molecules _____. provides the energy needed for tubulin to polymerize. occurs because the pool of free GDP has run out. tips the balance in favor of microtubule assembly. allows the behavior of microtubules called dynamic instability.

allows the behavior of microtubules called dynamic instability.

In the laboratory, you are working with a cell line that forms coated pits but the vesicles do not detach from the parent membrane and the removal of coat proteins doesn't happen. Which of the following proteins might be lacking in this cell line? adaptin Rab clathrin dynamin

dynamin

Signal sequences that direct proteins to the correct compartment are always removed once a protein is at the correct destination. added to proteins through post-translational modification. encoded in the amino acid sequence and sufficient for targeting a protein to its correct destination. added to a protein by a protein translocator.

encoded in the amino acid sequence and sufficient for targeting a protein to its correct destination.

In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins? on the rough ER in the lumen of the ER in the cytosol the nucleus

in the cytosol

A protein kinase can act as an integrating device in signaling if it catalyzes its own phosphorylation. phosphorylates more than one substrate. is activated by two or more proteins in different signaling pathways. initiates a phosphorylation cascade involving two or more protein kinases.

is activated by two or more proteins in different signaling pathways.

Irradiated mammalian cells usually stop dividing and arrest at a G1 DNA damage checkpoint. Which of the following would occur first? p53 is ubiquitylated. Production of p21 Inhibition of cyclin-Cdk complexes. p53 is phosphorylated.

p53 is phosphorylated.

Which of the following structures shorten during muscle contraction? actin filament mysosin filament z disc sarcomere

sarcomere

Proteins that are fully translated in the cytosol do not end up in the cytosol. transport vesicles. the mitochondria. the interior of the nucleus.

transport vesicles