Cell Cycle Control And Cell Division Part I- Exam IV Flashcards
The cell cycle involves what two phases in order to create two identical daughter cells:
- Replication phase
- Division phase
What triggers the major events of the cell cycle?
Cell cycle control system
As the cell cycle proceed a serious of ___ ensure that each phase is complete before the next one begins
Checkpoints
How many major checkpoints are the eukaryotic cell cycle
3
What controls cell proliferation?
Cell-cycle control machinery
Inappropriate cell proliferation:
Cancer
Many of the genes (proteins) involved in the cell cycle regulation are critical:
Determinants of cancer progression
G1 and G2 are the ____ phases of the cell cycle
Gap phases
Phase of the cell cycle where DNA synthesis takes place:
S phase
Phase of the cell cycle in which division takes place
M phase
The 3 important checkpoints of the cell cycle occur during:
- Late G1checkpoint
- G2M checkpoint
- Metaphase to anaphase transition checkpoint
Checkpoint in late G1 checks for:
if the environment is favorable for cell division
In the late G1 checkpoint, what is being checked in the environment?
- Hormone signals
- Appropriate nutritions
- Etc
The G2M checkpoint:
Replication of DNA & favorable environment
If at the G2M checkpoint, the cell determines it can go on it will enter:
M phase
The cell won’t separate the chromosomes and split without the go ahead from the:
Metaphase to anaphase transition checkpoint
Check point that asks: Is the environment favorable?
Late G1 checkpoint (start checkpoint)
Check point that asks: Is all the DNA replicated? Is the environment favorable?
G2/M checkpoint
Check point that asks:
Are all the chromosomes attached to the spindle?
Metaphase to anaphase transition checkpoint
After the G1S checkpoint, the cell proceeds to:
After the G2M checkpoint, the cell proceeds to:
After the metaphase to anaphase transition checkpoint, the cell enters:
- Enters cell cycle and proceeds to S phase
- Enters mitosis
- Triggers anaphase and proceeds to cytokinesis
The cell-cycle checkpoint control system depends on:
- Cyclically activated cyclin-dependent protein kinases (CDKs)
- Cyclical proteolytic events
- Transcriptional regulation
Triggers the events that occur in each phase of the cell cycle:
Cell-cycle control system
The cell-cycle control system ensures the proper ____, ____, and ______ of the events.
Timing, order, fidelity
What type of signals does the cell-cycle control system respond to?
Intracellular & extracellular signals
Whenever the cell fails to complete an essential cell-cycle process or encounters unfavorable intracellular or extracellular conditions, the cell-cycle control system:
Arrests
Important critical determinants of the mammalian cell cycle:
Cyclin- CDKs
Where the cell gets pulled out of the normal cell cycle and is put into a quiescent state:
G0
Cyclins and cyclin dependent kinases are critical determinants for the transition of:
One cell cycle phase to the next
For cyclin dependent kinases to become activated, what event must first occur:
The binding of the specific cyclin that recognizes the CDK creating a complex
Following the binding of the specific cycling to the CDK creating a complex, what takes place?
Subsequent specific phosphorylation reactions
The specific phosphorylations that take place on the cyclin-CDK complex, turn this complex into an:
Activated state
If the cyclin is not present, the CDK will be:
Inactive
The initial checkpoint that occurs in late G1 involves what cyclin?
G1/S cyclin pair
The G1/S cyclin pair comes up and reaches a peak in ______, and when the cell moves from G1 into S this cyclin_____.
Late G1; falls off
The S-cyclin is necessary for:
Starting synthesis
As the G1/S cyclin is falling off, the S-cyclin:
Begins to work
As we reach into the mitosis phase, the S-cyclin ______, and an M cyclin has reached a ____,
Falls off; critical level
When does the M-cyclin level decrease?
Metaphase to anaphase transitions
The cyclin molecules ____ in their concentration because they are ____.
Oscillate ; Induced
_____ has the enzymatic activity in the cell cycle:
CDKs
The concentrations of the three major cyclin proteins oscillate during the cell cycle; their expression is _____ to promote transitions through the cell cycle
Induced
The concentrations of CDK do not change because they are:
Constitutively expressed
Critical for determining transitions from one phase of the cell-cycle to the next:
Appearance and disappearance of cyclins
In addition to the specific necessary cyclins, the _______ or ______ initiates the metaphase to anaphase transition.
Anaphase-promoting complex or Cylcosome (APC/C)
There are 3 D cyclins in mammals including:
Cyclins D1, D2, and D3
During the cell cycle process, the CDKs are consituitively expressed in an:
Inactive state
The CDKs only become activated if the:
Proper cyclin molecule is expressed
Why are the CDKs originally inactive?
Because the active site is blocked by T-loop
What molecule is the T-loop covering and on?
CDK
The T-loop folds over the active site and prevents it from:
Phosphorylating or doing its action
When the cyclin binds to the CDK, this causes the T-loop to:
Change its configuration
When the T-loop changes it configuration due to the binding of the cyclin, this results in:
A partially activated molecule
In order for the CDK to become fully activated, there is an enzyme called ______ that comes in and phosphorylates the T-loop
CDK activating kinase (CAK)
The CAK is responsible for:
Phosphorylating the T-loop
Where does the CAK phosphorylate the T-loop?
At a very specific threonine
When the threonine of the T-loop gets phosphorylated by the CAK this results in:
Fully activated CDK
