BIO 320 (De Lozanne/ O Halloran) - Test 3 With
Complete Solutions
Cyclin-dependent kinases (Cdk) can be regulated by all of the following mechanisms
EXCEPT:
Binding of Cdk inhibitors
Cyclin degradation
Phosphorylation of the Cdk
Cdk degradation
Changes in Cyclin concentration - ANSWER Cdk Degradation
How is the synthesis of S-Cyclin stimulated?
By the degradation of the E2F inhibitor
By the activation of the transcription factor Rb protein
G1/S-CDK inactivates the Rb protein by phosphorylation
G1-CDK inactivates the E2F factor
G1-CDK acts as a transcription factor for the S-Cyclin gene - ANSWER G1/S-CDK
inactivates the Rb protein by phosphorylation
Which of the following is a CORRECT sequence of events necessary for entry into
S-phase?
Cdc6 is ubiquitylated by S-cdk, this causes firing of the origin of replication.
Cdc6 is phosphorylated by S-cdk, then MCMs and ORC are recruited to the
pre-Replicative complex (Pre-RC).
Cdc6 binds to ORC, then MCMs bind the cdc6-ORC complex to form the Pre-RC.
S-cdk is activated by the binding of E2F to the Pre-RC
ORC is phosphorylated by S-cdk, then Cdc6 and MCMs bind to ORC to form the Pre-RC.
- ANSWER Cdc6 binds to ORC, then MCMs bind the cdc6-ORC complex to form the
Pre-RC.
,You fuse a cell in S-phase with one in M-phase. What would be a likely observation in this
fused cell?
The chromosomes of the cell in M phase will decondense.
Non-phosphorylated condensins from the cell in S-phase will get phosphorylated.
The chromosomes of the cell in M phase are induced to replicate again.
Non-phosphorylated ORC from the cell in M-phase will get phosphorylated.
Nothing happens to the chromosomes of either cell. - ANSWER Non-phosphorylated
condensins from the cell in S-phase will get phosphorylated.
The function of Cohesins is to:
Bind to the centromere and form the kinetochore.
To condense a DNA chromatid by coiling DNA
Adhere the kinetochore to the microtubules.
Adhere two sister chromatids together.
Bind to condensins on the chromosome. - ANSWER Adhere two sister chromatids
together.
What would be the effect of artificially DECREASING the activity of CDC25 in the cell?
The cell would grow smaller.
The phosphorylation of Cdc25 would be delayed
The cell cycle would get shorter.
The activation of APC/Cdc20 would occur faster.
The removal of inhibitory phosphates from S-Cdk would be delayed. - ANSWER The
phosphorylation of Cdc25 would be delayed
During the G2 Checkpoint damage to DNA results in:
The degradation of M-cyclin
The activation of the M-Cdk specific CKI
, The export of Cdc25 from the nucleus
The inactivation of M-Cdk by caffeine
The ubiquitin-mediated degradation of CKI - ANSWER The export of Cdc25 from the
nucleus
Which of the following sequence of events occur before entry into M-phase?
Newly synthesized Cdk binds to M-Cyclin, Cdk is then phosphorylated by CAK and
Wee1.
Cdk is dephosphorylated by Cdc25, Cdk can then bind to M-cyclin to form the M-Cdk
complex.
Phosphorylation of M-cyclin by CAK induces the formation of the M-Cdk complex
Newly synthesized M-cyclin binds to Cdk, Cdk is then phosphorylated by CAK and
Wee1.
CAK phosphorylates Cdk which then binds M-cyclin , the complex is then
phosphorylated by Wee1. - ANSWER Newly synthesized M-cyclin binds to Cdk, Cdk is
then phosphorylated by CAK and Wee1.
The nuclear envelope is dismantled at the end of _______ and reformed during ______.
Interphase Prophase
Prophase Anaphase
Prophase Telophase
Metaphase Interphase
Telophase Metaphase - ANSWER Prophase Telophase
The Mitotic Spindle is formed during _______ by the activity of (+) end directed motors on
_________.
prometaphase--- astral microtubules
prophase--- kinetochore microtubules
prometaphase --- spindle poles
prophase--- overlap microtubules
Complete Solutions
Cyclin-dependent kinases (Cdk) can be regulated by all of the following mechanisms
EXCEPT:
Binding of Cdk inhibitors
Cyclin degradation
Phosphorylation of the Cdk
Cdk degradation
Changes in Cyclin concentration - ANSWER Cdk Degradation
How is the synthesis of S-Cyclin stimulated?
By the degradation of the E2F inhibitor
By the activation of the transcription factor Rb protein
G1/S-CDK inactivates the Rb protein by phosphorylation
G1-CDK inactivates the E2F factor
G1-CDK acts as a transcription factor for the S-Cyclin gene - ANSWER G1/S-CDK
inactivates the Rb protein by phosphorylation
Which of the following is a CORRECT sequence of events necessary for entry into
S-phase?
Cdc6 is ubiquitylated by S-cdk, this causes firing of the origin of replication.
Cdc6 is phosphorylated by S-cdk, then MCMs and ORC are recruited to the
pre-Replicative complex (Pre-RC).
Cdc6 binds to ORC, then MCMs bind the cdc6-ORC complex to form the Pre-RC.
S-cdk is activated by the binding of E2F to the Pre-RC
ORC is phosphorylated by S-cdk, then Cdc6 and MCMs bind to ORC to form the Pre-RC.
- ANSWER Cdc6 binds to ORC, then MCMs bind the cdc6-ORC complex to form the
Pre-RC.
,You fuse a cell in S-phase with one in M-phase. What would be a likely observation in this
fused cell?
The chromosomes of the cell in M phase will decondense.
Non-phosphorylated condensins from the cell in S-phase will get phosphorylated.
The chromosomes of the cell in M phase are induced to replicate again.
Non-phosphorylated ORC from the cell in M-phase will get phosphorylated.
Nothing happens to the chromosomes of either cell. - ANSWER Non-phosphorylated
condensins from the cell in S-phase will get phosphorylated.
The function of Cohesins is to:
Bind to the centromere and form the kinetochore.
To condense a DNA chromatid by coiling DNA
Adhere the kinetochore to the microtubules.
Adhere two sister chromatids together.
Bind to condensins on the chromosome. - ANSWER Adhere two sister chromatids
together.
What would be the effect of artificially DECREASING the activity of CDC25 in the cell?
The cell would grow smaller.
The phosphorylation of Cdc25 would be delayed
The cell cycle would get shorter.
The activation of APC/Cdc20 would occur faster.
The removal of inhibitory phosphates from S-Cdk would be delayed. - ANSWER The
phosphorylation of Cdc25 would be delayed
During the G2 Checkpoint damage to DNA results in:
The degradation of M-cyclin
The activation of the M-Cdk specific CKI
, The export of Cdc25 from the nucleus
The inactivation of M-Cdk by caffeine
The ubiquitin-mediated degradation of CKI - ANSWER The export of Cdc25 from the
nucleus
Which of the following sequence of events occur before entry into M-phase?
Newly synthesized Cdk binds to M-Cyclin, Cdk is then phosphorylated by CAK and
Wee1.
Cdk is dephosphorylated by Cdc25, Cdk can then bind to M-cyclin to form the M-Cdk
complex.
Phosphorylation of M-cyclin by CAK induces the formation of the M-Cdk complex
Newly synthesized M-cyclin binds to Cdk, Cdk is then phosphorylated by CAK and
Wee1.
CAK phosphorylates Cdk which then binds M-cyclin , the complex is then
phosphorylated by Wee1. - ANSWER Newly synthesized M-cyclin binds to Cdk, Cdk is
then phosphorylated by CAK and Wee1.
The nuclear envelope is dismantled at the end of _______ and reformed during ______.
Interphase Prophase
Prophase Anaphase
Prophase Telophase
Metaphase Interphase
Telophase Metaphase - ANSWER Prophase Telophase
The Mitotic Spindle is formed during _______ by the activity of (+) end directed motors on
_________.
prometaphase--- astral microtubules
prophase--- kinetochore microtubules
prometaphase --- spindle poles
prophase--- overlap microtubules
