Cell Cycle Control & 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 proceeds, a series of ______ ensure that each phase is complete before the next one begins
Checkpoints
How many many major checkpoints are in the eukaryotic cell cycle
Three
What control 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 & G2 are the ____ phases of the cell cycle
Gap phases
Phase of the cell cycle in which DNA synthesis takes place
S phase
Phase of the cell cycle in which division takes place
M phase
The three important check points occur during:
late G1 checkpoint
G2/M 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 to insure favorable conditions:
Hormone signals, nutrients, etc.
The G2/M check points is assessing whether:
Correct replication of DNA
Favorable environment
If at the G2/M checkpoint the cell determines it can go on, it will enter the:
M phase
The cell won’t separate the chromosome & split without the go ahead from the:
Metaphase to anaphase transition checkpoint
Checkpoint that asks:
Is the environment favorable
Late G1 checkpoint (start checkpoint)
Checkpoint that asks:
Is all the DNA replicated
Is the environment favorable
G2/M checkpoint
Checkpoint that asks:
Are all the chromosomes attached to the spindle
Metaphase to anaphase transition checkpoint
After the G1/S checkpoint the cell proceeds to:
After the G2M checkpoint, the cell proceeds to:
After the metaphase to anaphase transition checkpoint, the cell proceeds to:
Enters the cell cycle and proceeds to S phase
Enters mitosis
Triggers anaphase & proceeds to cytokinesis
The cell-cycle checkpoint control system depends on:
1- Cyclically activated cyclin-dependent protein kinases (Cdks)
2- Cyclical proteolytic events
3- transcriptional regulation
Triggers the events that occur in each phase of the cell cycle:
Cell-cycle control system
The cell-cycle control system insures the proper _____, _____ & _____ of the events
Timing, order & fidelity
Type of signals the cell-cycle control system responds 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 to the mammalian cell cycle:
Cyclin-dependent kinases (Cyclin-Cdks)
Where the cell gets pulled out of the normal cell cycle & is put into a quiescent state:
G0 phase
Cyclins & cyclin-dependent kinases are critical determinants for the transition of:
One cell cycle phase to the next
For the cyclin-dependent kinases to become activated what first must occur:
binding of the specific cyclin that recognizes that CDK to create a complex
Following the binding of the specific cyclin to the CDK, creating a complex, what takes place:
Subsequent specific phosphorylations
The specific phosphorylations that take place on the cyclin-CDK complex turn this complex into a:
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 _____ & then the as the cell moves from G1 to S this cyclin:
Late G1
Falls off
The S-cyclin is necessary for the start of:
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 the M-cyclin has reached a _____
Falls off
Critical level
When does the M-cyclin level decrease:
Metaphase to anaphase transition
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 express is _____ to promote transitions through the cell cycle
Induced
The concentrations of the Cdk do not change because they are:
Constitutively expressed
Critical for determining transitions from one phase of the cell-cycle to the next
appearance/disappearance of cyclins
In addition the specific necessary cyclin, the _______ or _____ initiates the metaphase to anaphase transition
Anaphase-promoting complex or cyclosome (APC/C)
There are three D cyclins in mammals including:
Cyclins D1, D2 & D3
During the cell-cycle processs, the CDKs are constitutively expressed in an:
Inactive state
CDKs only become activate if the:
Proper cyclin molecule is expressed
Why are the CDKs originally inactive:
Due to active site being blocked by T-loop
What molecule is the T-loop covering & on
CDK
The presence of the T-loop (folded over the active site) prevents it from:
Phosphorylating
When the cyclin binds to the CDK this causes the T-loop to:
Change its configuration
When the T-loop changes its configuration due to the binding of the cyclin this results in:
A partially activated CDK
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:
Very specific threonine
