Stony Brook University BIO 310/BIO310 All Lecture quizzes (answered) study this for a 100% A grade.
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BIO 310 (BIO310)
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Stony Brook University
Quiz questions based on Lecture 13 (Signaling-1).
1. What is always present in a signaling pathway?
A. Signal that originates outside a cell
B. Signal that remains outside the responding cell during signaling
C. Cell-surface receptor
D. A and B are correct
2. Adrenaline is a signal used in th...
1. What is always present in a signaling pathway?
A. Signal that originates outside a cell
B. Signal that remains outside the responding cell during signaling
C. Cell-surface receptor
D. A and B are correct
2. Adrenaline is a signal used in the fight-or flight response. Adrenaline signaling is
A. Endocrine
B. Paracrine
C. Autocrine
D. Contact-dependent
3. One signal can have different effects on the same cell; for example, it can alter both
metabolism and gene expression. This occurs when
A. One activated receptor binds several effector proteins
B. One effector protein causes several responses
C. One intracellular signaling molecule activates several effector proteins
D. One effector protein activates several intracellular signaling molecules
4. What is true of signaling molecules that bind intracellular receptors?
A. They are linked to enzymes
B. They always act in an autocrine manner
C. They always act in a paracrine manner.
D. They easily diffuse across the plasma membrane
5. What is true of an inactive G protein?
A. It is not attached to the plasma membrane
B. It is bound tightly to an inactive receptor
C. It keeps its target protein inactivated by binding to it
D. It is a heterotrimer (3 different polypeptide subunits)
6. What is the first step in activation of a G-protein coupled receptor signaling pathway?
A. A ligand (small signaling molecule) binds a cell-surface receptor
B. A ligand binds the alpha subunit of a G protein
C. A cell-surface receptor binds GTP
D. The alpha subunit of a G protein binds GTP
7. What is true of an activated G protein?
A. It is released from the plasma membrane into the cytosol
B. It is a heterotrimer (3 different polypeptide subunits)
C. The alpha subunit is bound to GTP
D. The beta subunit is bound to GTP
,8. What is important in turning off (inactivating) G protein signaling?
A. Binding of an inactive G protein to a target protein
B. Hydrolysis of GTP to GDP
C. Separation of the G protein alpha subunit from the beta-gamma complex
D. Release of the G protein from the plasma membrane into the cytosol
,Quiz on Lecture 14, Signaling-2 (review session 3/29/21)
1. What is true of EGFR (EGF receptor)?
A. Only one EGFR monomer in a dimer is ever activated; it phosphorylates several Tyr on the other
monomer.
B. EGFR phosphorylates substrates (including Ras) on Tyr to activate them.
C. EGFR is activated by a cytosolic kinase, which phosphorylates EGFR on Tyr residues.
D. EGF binding changes EGFR conformation to allow its dimerization.
2. Two proteins, Grb2 and Cbl, are both recruited to the cytoplasmic domain of EGFR after EGFR is
activated. What is true?
A. Grb2 and Cbl compete with each other to bind EGFR, since they both bind the same site (P-Tyr)
B. Cbl binds directly to EGFR P-Tyr, while Grb2 is recruited indirectly to EGFR by binding to Sos
C. Grb2 and Cbl each bind two sites on EGFR: both a specific P-Tyr, and also a second site nearby
D. Grb2 binds a specific P-Tyr on EGFR, while Cbl binds to monoubiquitinated EGFR
3. Ras
A. Is recruited to the plasma membrane by binding to Sos, a Ras-GEF
B. Binds activated EGFR via its SH2 domain
C. Initiates a kinase cascade when activated
D. Binds to Erk when activated
4. The duration of Ras activation following EGF addition to cells was measured using a FRET assay.
What is true of FRET assays in general, and this experiment in particular?
A. In FRET experiments in general, one fluorescent protein absorbs light emitted by a second fluorescent
protein.
B. In this experiment, FRET decreased as GTP was hydrolyzed.
C. In this experiment, FRET was used to test whether Ras and Sos (a Ras GEF) bind each other.
D. Both A and B are correct.
5. Akt
A. Is recruited to the plasma membrane by binding PI(3,4,5)P3
B. Is phosphorylated by PDK1
C. Is phosphorylated by mTOR (in a complex with other proteins)
D. A, B, and C are correct
6. You express a mutant Akt that has no kinase activity in cells, while blocking expression of any wild-
type Akt. What happens?
A. Bad binds an apoptosis-inhibitory protein.
B. Bad binds 14-3-3.
C. Bad is phosphorylated by PDK-1.
D. Both A and B are correct.
7. Receptor tyrosine kinase signaling eventually leads to degradation of the receptor. What is a step in
this pathway?
A. The ubiquitin ligase Cbl binds to a P-Tyr on the receptor
B. An arrestin binds to a phosphorylated tyrosine on the receptor
C. Ubiquitination targets a receptor for degradation by the proteasome
D. Both A and C are correct
8. What is important in reducing (turning off) GPCR signaling?
A. GPCR phosphorylation
B. Arrestin binding to GPCR to block G protein binding
C. Removal of the GPCR from the plasma membrane by endocytosis
D. All of the above
, Quiz on Lecture 15 Cytoskeleton-1 (actin)
1. What is true of actin treadmilling in vitro (no proteins other than purified actin present)?
A. Actin filaments get shorter.
B. Actin monomers are added to the plus and minus ends of filaments at the same rate.
C. ATP is hydrolyzed by the actin-ATP monomers in solution at the same rate that monomers are added
to the filament plus ends
$D. The actin monomer concentration is lower than the critical concentration of the minus end.
2. You divide a solution of purified actin monomers between 2 tubes, then add pre-formed actin
filaments to Tube A only (no filaments added to Tube B), and observe the tubes over time. What is
true?
$A. For the first few minutes, filament growth rate is faster in Tube A than Tube B.
B. Filament growth rate is faster in Tube A at all times (including the first few minutes), until steady
state is reached.
C. Tube A and Tube B reach steady state at the same time.
D. Choices A and B are both correct
3. Arp 2 and Arp 3
A. Can be incorporated into new actin filaments, at the minus ends
B. Are present in a protein complex that overcomes the slow lag phase in actin polymerization
C. Are both structurally similar to actin
$D. A, B, and C are correct
4. What keeps the concentration of actin monomers higher in cells than would be expected from the
behavior of purified actin in vitro?
$A. Binding to thymosin
B. Binding to CapZ
C. Continual activity of cofilin
D. High rate of ATP hydrolysis by actin-ATP monomers in cells
5. Formins
A. Stimulate actin polymerization by binding to and stabilizing filament minus ends
$B. Have a domain that forms dimers, which encircle growing actin filaments
C. Make branched actin filaments
D. A and B are both correct
6. What provides the driving force to move the front of a migrating cell forward?
A. Actin-myosin contractile bundles push against the plasma membrane
B. Filopodia protrude from the leading edge
$C. Arp 2/3-dependent polymerization forms actin filaments that push against the plasma membrane
D. Actin treadmilling pushes against the plasma membrane
7. Why are integrins necessary in cell migration?
A. Integrins send signals that stimulate actin polymerization at the leading edge.
$B. Integrins link actin filaments to the extracellular matrix, anchoring them and allowing them to push
the plasma membrane forward.
C. Integrins send signals that slow actin disassembly at the leading edge.
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