- BIO320 Lectures 19-22
Cell Cycle
iClicker questions and additional slides
THIRDMIDTERMEXAM
THURSDAYMAY3TH
7:00PM8:30PMJESA121A
Question # 1
What would happen if you fused together two cells,
one in G1-phase and one in M-phase
A)
B)
C)
D)
E)
The nucleus of the cell in G1 will start DNA
replication
The nucleus of the cell in G1 will enter M-phase
The nucleus of the cell in M-phase will enter G1phase
The nucleus of the cell in M-phase will start DNA
replication
The two nuclei will keep going through their
respective phases of the cell cycle
Question # 1
What would happen if you fused together two cells,
one in G1-phase and one in M-phase
A)
B)
C)
D)
E)
The nucleus of the cell in G1 will start DNA
replication
The nucleus of the cell in G1 will enter M-phase
The nucleus of the cell in M-phase will enter G1phase
The nucleus of the cell in M-phase will start DNA
replication
The two nuclei will keep going through their
respective phases of the cell cycle
Cell Fusion shows that cells contain protein
factors that induce mitosis
Karp 14-3
What happens if you fuse a G1-cell
with an S-Cell? Or other combinations?
Question # 2
What would happen if a cell did not have Wee1?
A)
B)
C)
D)
E)
M-Cdk would not be activated
M-cyclin would not be synthesized
M-cyclin would not be phosphorylated
The activity of M-Cdk would rise proportionally to
the synthesis of M-cyclin
M-Cdk would be phosphorylated by CAK but it
would not trigger entry into M-phase
Question # 2
What would happen if a cell did not have Wee1?
A)
B)
C)
D)
E)
M-Cdk would not be activated
M-cyclin would not be synthesized
M-cyclin would not be phosphorylated
The activity of M-Cdk would rise proportionally to
the synthesis of M-cyclin
M-Cdk would be phosphorylated by CAK but it
would not trigger entry into M-phase
Question # 1
What statement is wrong based on Figure 17-16?
A)
B)
C)
D)
E)
There is a specific cyclin for each phase of the
cell cycle
All cyclins bind to a CDK protein
All CDK proteins are inactive if they dont have a
cyclin bound to them
All cyclins are destroyed at some point of the cell
cycle
There are times in the cell cycle when there are
NO cyclin proteins present
Question # 1
What statement is wrong based on Figure 17-16?
A)
B)
C)
D)
E)
There is a specific cyclin for each phase of the
cell cycle
All cyclins bind to a CDK protein
All CDK proteins are inactive if they dont have a
cyclin bound to them
All cyclins are destroyed at some point of the cell
cycle
There are times in the cell cycle when there are
NO cyclin proteins present
Question # 2
What would be the effect of having a reduced amount
of Rb protein in a cell?
A)
B)
C)
D)
E)
G1-Cdk would not be active
S-Cdk would not be activated
G1/S cyclin would not be synthesized
The cell would enter S-phase prematurely
The E2F factor would be inactivated
Question # 2
What would be the effect of having a reduced amount
of Rb protein in a cell?
A)
B)
C)
D)
E)
G1-Cdk would not be active
S-Cdk would not be activated
G1/S cyclin would not be synthesized
The cell would enter S-phase prematurely
The E2F factor would be inactivated
Question # 3
What would be the effect of making a mutant of Cdc6 protein that cannot be phosphorylated?
A)
B)
C)
D)
E)
Cdc-6 would not bind to ORC
DNA replication could not initiate
DNA replication would start multiple times from
one origin
The cell would enter S-phase prematurely
Cdc-6 would not be degraded
Question 3
What # would be the effect of making a mutant of Cdc6 protein that cannot be phosphorylated?
A)
B)
C)
D)
E)
Cdc-6 would not bind to ORC
DNA replication could not initiate
DNA replication would start multiple times from
one origin
The cell would enter S-phase prematurely
Cdc-6 would not be degraded
Question # 1
You study a cell where G1-cdk has been activated
and see that Rb is phosphorylated. If you then
inhibit the activity of G1-Cdk you observe that the
cell contains unphosphorylated Rb protein. Why?
A)
B)
C)
D)
E)
The phosphorylation is degraded
The phosphate is removed by a phosphatase
Phosphorylated Rb is degraded
Unphosphorylated Rb is synthesized
G1/S-Cdk replaced the activity of G1-Cdk
Question # 1
You study a cell where G1-cdk has been activated
and see that Rb is phosphorylated. If you then
inhibit the activity of G1-Cdk you observe that the
cell contains unphosphorylated Rb protein. Why?
A)
B)
C)
D)
E)
The phosphorylation is degraded
The phosphate is removed by a phosphatase
Phosphorylated Rb is degraded
Unphosphorylated Rb is synthesized
G1/S-Cdk replaced the activity of G1-Cdk
Question # 2
What would be a likely consequence of making a
mutation in the protein Lamin that removes any
potential phosphorylation site?
A)
B)
C)
D)
E)
The nuclear envelope will be dismantled in G1
Chromosomes will not condense in Prophase
Chromosomes will condense in Prometaphase
Microtubules will not attach to kinetochores
The mitotic spindle will not form
Question # 2
What would be a likely consequence of making a
mutation in the protein Lamin that removes any
potential phosphorylation site?
A)
B)
C)
D)
E)
The nuclear envelope will be dismantled in G1
Chromosomes will not condense in Prophase
Chromosomes will condense in Prometaphase
Microtubules will not attach to kinetochores
The mitotic spindle will not form
Chromosome condensation is caused by Condensins
SMC proteins similar to
those found in Cohesins
Activated by phosphorylation by M-Cdk
Alberts 4-73 & 17-27
Many Microtubule Motor Proteins work on the Spindle
KRP(-)
KRP(+)
chromokinesin
Alberts 17-30
Question # 1
Imagine you can increase the activity of particular
motors in the spindle. Which motor would you
increase to make the spindle shorter?
A)
B)
C)
D)
E)
Chromokinesin
Dynein at cell cortex
KRP (+) on overlap MTs
KRP (-) on overlap MTs
Kinetochore KRP
Question # 1
Imagine you can increase the activity of particular
motors in the spindle. Which motor would you
increase to make the spindle shorter?
A)
B)
C)
D)
E)
Chromokinesin
Dynein at cell cortex
KRP (+) on overlap MTs
KRP (-) on overlap MTs
Kinetochore KRP
Daughter DNA strands are held together by Cohesins
Alberts 17-24
Loaded during DNA Replication
Question # 2
Caffeine is a drug that inhibits the G2 Checkpoint. (to
know how much do Homework #8) You add
caffeine to a normal healthy cell that is in G2.
What is likely to happen?
A)
B)
C)
D)
E)
The cell will go back to S phase
The cell will stop in G2
The cell will continue to M phase
The cell will stop in M phase
The cell will die
Question # 2
Caffeine is a drug that inhibits the G2 Checkpoint. (to
know how much do Homework #8) You add
caffeine to a normal healthy cell that is in G2.
What is likely to happen?
A)
B)
C)
D)
E)
The cell will go back to S phase
The cell will stop in G2
The cell will continue to M phase
The cell will stop in M phase
The cell will die