II. Multiple Choice
1. One difference between receptor-mediated apoptosis and mitochondria-mediated apoptosis is that
a. receptor-mediated apoptosis makes use of procaspase-9
b. FADD and TRADD serve as protein kinases in receptor-mediated apoptosis
c. mitochondria-mediated apoptosis makes use of executioner caspases
d. mitochondria-mediated apoptosis involves the movement of cytochrome c into the cytoplasm
e. TNF stimulates mitochondria-mediated apoptosis
2. Which if the following statement about the apoptotic process is TRUE?
a. Anti-apoptotic protein BCL-2 is located in the mitochondrial inner membrane
b. Apoptotic protein Bax resides in cytosol and translocates into the mitochondria in response to
c. Cytochrome C is released from lysosome into cytosol to kill the cell
d. During apoptosis, there is an increase in osmotic pressure inside the cell, causing the cell to swell
and burst and results in cell death
3. Which of the following is TRUE about G-protein signaling?
I. During activation of G-protein, subunit of the G-protein dissociates from the activated G-protein to activate adenylyl cyclase
II. During activation of G-protein, the active α subunit is terminated by the hydrolysis of the bound GTP caused by GTPase
III. Testosterone can bind to the cell membrane receptor to activate G-protein
IV. The ratio of G-protein coupled receptor to G-protein is 1:1
a. I only
b. II only
c. III only
d. II and IV
e. II and III
4. What is/are the consequences of the activation of phospholipase C (PLC) by G protein mechanism?
a. Cleavage of phophotidylinositol 4,5-bisphosphate (PIP2) into IP3 and protein kinase C (PKC)
b. Decrease of Ca2+ level in the cell causes cell mobility
c. IP3 binds to receptor on the membrane of the ER to stimulate the release of Ca2+
d. Diacylglyercol (DAG) alone activates protein kinase C (PKC)
5. What would be the likely result of a mutation of the bcl-2 gene on the level of apoptosis?
a. no change
b. a decrease in apoptosis
c. an increase in apoptosis
d. first it would increase but later it would decrease
6. What is the biggest difference between necrosis and apoptosis?
a) necrosis is unregulated cell death and hence is wasteful of cellular components, while apoptosis is highly regulated and allows for recycling of cellular structures.
b) necrosis is cell death but apoptosis causes cell growth
c) necrosis requires activation of MAP kinase but apoptosis does not
d) necrosis is mediated by a series of protein phosphorylation step while apoptosis is mediated b y a series of protease activation steps
3) necrosis happens slower than apoptosis but otherwise they are identical
7. Which of the following signaling molecules stimulates a rise in cytosolic Ca2+?
b. Inositol tripphosphate
c. MAP kinase
8. Which of the following statements is false?
a. G protein-linked receptors span the plasma membrane seven times, tyrosine kinase-linked receptors span the membrane once per polypeptide chain.
b. G protein-linked receptors form dimmers when activated, tyrosine kinase-linked receptors do not
c. G protein-linked receptors activate adenylate cyclase signaling pathways, tyrosine kinase-linked receptors do not
d. Both G protein-linked receptors and tyrosine kinase-linked receptors are expressed on the plasma membrane
e. Both G protein-linked receptors and tyrosine kinase-linked receptors contain signal sequences that target them to the endoplasmic reticulum
9. Which of the following statements about phospholipase C proteins is false?
a. They are found in the plasma membrane
b. They bind to Gp and to phosphotyrosines on growth factor receptors
c. They induce the formation of diacyl glyercol (DAG) in the plasma membrane but not in the ER
d. They are monomers
e. They complex with co-SMADS to induce activation of SMADs
10. Select the proper temporal sequence of signaling events associated with growth factor binding to the cell surface.
i. Autotransphosphorylation of receptor
ii. Phosphorylation of MAP kinase
iii. Binding of Grb2 to SOS
iv. Dimerization of receptor
v. Exchange of GDP for GTP
a. i, iv, iii, ii, v
b. iv, i, iii, v, ii
c. i, iv, iii, v, ii
d. iv, i, iii, ii, v
e. iv, iii, i, ii, v
11. Which of the following is the most accurate description of the mechanism of apoptosis?
a. A cell receives external signals that initiate a cascade of protease activation events in the cytosol; the activated proteases digest the cell from the inside-out, so that none of the cellular proteins leaks into the extracellular space.
b. A cell receives external signal that stimulate the neighboring cells to engulf it, the cellular contents are eventually digested in the lysosome soothe neighboring cells
c. A c cell receives external signals that cause the cell to secrete proteases that digests the surrounding extracellular matrix; the loss of contact with ECM causes the plasma membrane to rupture and the cell “bleeds to death”
d. Apoptosis is also known as “programmed cell death” and thus it is driven by a signal that originates in the nucleus; the signal is transmitted to the cytosol where it is converted into protease proteins that digest the cell from the inside out
e. None of the above is more accurate than the others.
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