Cell Biology Exam 4

Which of the following kinases is responsible for phosphorylation and inactivation of M-Cdk? a) Wee1 kinase b) MAP kinase c) Akt kinase d) S-Cdk e) cdc25

a) Wee1 kinase

How does RB protein prevent escape from G0? a) by binding to and inhibiting E2F transcription factor b) by binding to and inhibiting p53 c) by phosphorylating p53 d) by binding to Cdk inhibitors like p21 e) RB protein promotes escape from G0

a) by binding to and inhibiting E2F transcription factor

Which of the following proteins is required to sustain G1 phase? a) cdh1 b) p53 c) cdc25 d) mTOR e) myc

a) cdh1

At the metaphase-anaphase transition, which of the following proteins is ubiquinated by APC? a) cyclin B b) cdc20 c) separase d) cohesins e) none of the above are ubiquinated by APC

a) cyclin B

Growth factors increase protein synthesis and decrease protein degradation by activating which of the following? a) mTOR b) cdh1 c) cdc20 d) p53 e) myc

a) mTOR

Which of the following events prevents a second round of DNA replication a) phosphorylation of ORC b) phosphorylation of cdc25 c) ubiquination of cyclin B d) ubiquination of cdc6 e) none of the above

a) phosphorylation of ORC

Complete the following sentence: Caspases are ... a) proteases b) phosphatases c) ubiquitin ligases d) scaffold proteins e) kinases

a) proteases

What is the energy source that drives chromosomal segregation during anaphase B? a) the electrochemical gradient across the plasma membrane b) ATP hydrolysis c) GTP hydrolysis d) catastrophic shortening of kinetochore microtubules e) the energy source is not known

b) ATP hydrolysis

Which of the following is phosphorylated by S-Cdk to initiate DNA synthesis a) DNA polymerase b) Cdc6 c) MPF d) ORC e) Helicase

b) Cdc6

Which of the following kinase-cyclin pairs is correctly matched? a) S Cdk & cyclin B b) G1-S Cdk & cyclin E c) M Cdk & cyclin C d) G1-Cdk & cyclin A e) All are correctly matched

b) G1-S Cdk & cyclin E

Which of the following phosphorylates and inactivates the Wee1 kinase at the onset of M-phase? a) p53 b) M-Cdk complex c) S-Cdk complex d) APC e) cdc25

b) M-Cdk complex

Which of the following events occurs during prometaphase? a) DNA replication b) disintegration of the nuclear envelope c) ubiquination of cyclin B d) inactivation of APC e) formation of the contractile ring

b) disintegration of the nuclear envelope

During apoptosis, how does cytochrome C get out of the mitochondrion? a) it leaves through channels formed by "BH3 only" proteins b) it leaves through channels formed by "BH123" proteins c) it aggregates to form clusters that are membrane permeable d) it binds to BH123 proteins and enters the cytosol e) it binds to Bcl2

b) it leaves through channels formed by "BH123" proteins

Mitogens promote entry into cell cycle by inactivating which of the following proteins? a) cdc20 b) p53 c) Rb d) cyclin D e) APC

c) Rb

Which of the following is phosphorylated by the M-Cdk complex? a) p53 b) securin c) nuclear lamin B d) p21 e) all of the above are substrates for M-Cdk

c) nuclear lamin B

Which of the following refers to the SMC protein complex that gathers and organizes newly replicated DNA into chromosomes ? a) gatherin b) compactin c) cohesin d) condensin e) compressin

d) condensin

How does cytochrome C initiate apoptosis? a) it promotes the aggregation of BH123 proteins in the outer membrane b) it aggregates to form channels in the outer mitochondrial membrane c) it directly activates executioner procaspases d) it promotes the recruitment of initiator procaspases e) none of the above

d) it promotes the recruitment of initiator procaspases

During G1 phase, which of the following prevents entry into S-phase when DNA damage is present? a) mTOR b) cdh1 c) cdc20 d) p53 e) myc

d) p53

What is the ultimate fate of apoptotic cells? a) they aggregate in tissue to form scars b) they are processed to simple compounds by their own enzymes c) they remain quiescent until activation of G1-S Cdk d) they are consumed by macrophages e) they emerge in a parallel universe as components of anti-creatures

d) they are consumed by macrophages

Some of the effects of growth factors are mediated through which of the following kinases? a) protein kinase A b) protein kinase C c) CAK d) Wee1 kinase e) Akt kinase

e) Akt kinase

MPF refers to the substance(s) present in the cytosol of unfertilized Xenopus oocytes that is capable of driving multiple cycles of M phase and S phase in vitro. What is MPF? a) Mitotic Progress Facilitator b) Metaphase Promoting Factor c) Momma's Powerful Force d) Metaphysical Procreation Factor e) Maturation Promoting Factor

e) Maturation Promoting Factor

Complete the following sentence: The anti-apoptotic protein, Bcl2, prevents apoptosis by ... a) returning cytochrome C to the mitochondrion b) promoting the aggregation of "BH123" proteins c) promoting the aggregation of "BH3 only" proteins d) preventing the aggregation of "BH3 only" proteins e) a mechanism that is not listed above

e) a mechanism that is not listed above

Which of the following refers to the phosphatase that activates M-Cdk to initiate M-phase? a) phosphatase B b) M phosphatase c) cdc6 d) cdc20 e) cdc25

e) cdc25

Which of the following refers to the proteins that are cleaved by separase to release sister chromatids at anaphase? a) anaphase promoting complex (APC) b) cyclin B c) condensins d) separins e) cohesins

e) cohesins

What is the role of the cyclin component of a cyclin-dependent protein kinase complex? a) it phosphorylates and activates the kinase b) it blocks the active site of the kinase c) it protects the kinase from ubquination d) it is a phosphatase e) it determines the substrate specificity of the kinase

e) it determines the substrate specificity of the kinase

During cytokinesis, which of the following motor proteins closes the contractile ring? a) dynein b) kinesin c) dynamin d) myosin I e) myosin II

e) myosin II