BIOL133 EXAM STUDY QUESTIONS AND
VERIFIED ANSWERS| 100% CORRECT
3 Main Checkpoints (Cell Cycle)
1. G1/S Checkpoint --> Point of no return!
Also arguable --> (Restriction Point) - Occurs right before G1/S Checkpoint
2. G2/M Checkpoint
3. Metaphase/Anaphase Checkpoint
What are cells checking for during checkpoints?
1. Am I big enough to divide? (G1/S)
2. Is my DNA intact? (G1/S)
3. Is my DNA replicated? (G2/M)
4. Are my chromosomes lined up correctly during mitosis/meiosis? (Metaphase/Anaphase)
The Cell Cycle Is Controlled By...
The CDK Family of proteins (Cyclin-Dependent Kinase)...
- Kinase (Regulation) proteins
- Phosphorylate targets
- Require activating protein --> Cyclin!
Cyclin In The Cell Cycle
- Different stages of the cell cycle have different cyclins expressed
- Activate the next cyclin in line!
,Cyclin Throughout The Cell Cycle
G1: CycD/CdK4 --> CycE/CdK2
S: CycA/CdK2 --> CycA/CdK1
G2: CycB/CdK1 --> Turned off in the middle of the M phase
M: No cyclin activity!
What activates CycD/CdK4?
External cell signals!
Stages Of Mitosis
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase A
5. Anaphase B
6. Telophase
7. (Cytokinesis)
Goal Of Mitosis
To create two genetically identical daughter cells capable of survival
Prophase
G2 --> M...
1. Chromosome condensation
2. Nuclear envelope breakdown
3. Centrosome migration/microtubule reorganization to opposite sides of the cell --> Driven by
kinesin and dynein!
Prometaphase
, Search and capture --> Grab kinetochores!
--> Each kinetochore on sister chromatids should be connected to a pole so both poles
are connected (2 per sister chromatid)
--> Oscillation to pull sister chromatids to the middle until aligned
Metaphase
- Sister chromatids are aligned in the middle of the cell...
--> Metaphase plate forms, cohesin is cut by separase to stop cohesion, resolution of
the metaphase/anaphase checkpoint, and sister chromatids are no longer attached!
Anaphase A
- Initial separation of chromosomes to poles...
--> Dynein pulls chromosomes towards periphery of the cell while Kinesin-13 is depolymerizing
MTs --> Chromosomes are pulled right up against spindle poles
Anaphase B
- Further separation of chromosomes by moving poles...
--> Elongates the cell!
MTs (Anaphase B)
1. Kinetochore MT --> MT attached to chromosomes and poles - (Spindles)
2. Astral MT --> MT attached to outside of poles and plasma membrane - (Dynein glued to
the cell cortex pulls poles towards the periphery of the cell)
3. Nonkinetochore MT --> MT attached to inside of poles moving towards the middle of the
cell - (Kinesin with 4 heads pushes force to separate the poles)
Telophase
- Anti-prophase...
--> Nuclear envelope reforms, chromosomes decondense, MTs rearrange
Cytokinesis
VERIFIED ANSWERS| 100% CORRECT
3 Main Checkpoints (Cell Cycle)
1. G1/S Checkpoint --> Point of no return!
Also arguable --> (Restriction Point) - Occurs right before G1/S Checkpoint
2. G2/M Checkpoint
3. Metaphase/Anaphase Checkpoint
What are cells checking for during checkpoints?
1. Am I big enough to divide? (G1/S)
2. Is my DNA intact? (G1/S)
3. Is my DNA replicated? (G2/M)
4. Are my chromosomes lined up correctly during mitosis/meiosis? (Metaphase/Anaphase)
The Cell Cycle Is Controlled By...
The CDK Family of proteins (Cyclin-Dependent Kinase)...
- Kinase (Regulation) proteins
- Phosphorylate targets
- Require activating protein --> Cyclin!
Cyclin In The Cell Cycle
- Different stages of the cell cycle have different cyclins expressed
- Activate the next cyclin in line!
,Cyclin Throughout The Cell Cycle
G1: CycD/CdK4 --> CycE/CdK2
S: CycA/CdK2 --> CycA/CdK1
G2: CycB/CdK1 --> Turned off in the middle of the M phase
M: No cyclin activity!
What activates CycD/CdK4?
External cell signals!
Stages Of Mitosis
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase A
5. Anaphase B
6. Telophase
7. (Cytokinesis)
Goal Of Mitosis
To create two genetically identical daughter cells capable of survival
Prophase
G2 --> M...
1. Chromosome condensation
2. Nuclear envelope breakdown
3. Centrosome migration/microtubule reorganization to opposite sides of the cell --> Driven by
kinesin and dynein!
Prometaphase
, Search and capture --> Grab kinetochores!
--> Each kinetochore on sister chromatids should be connected to a pole so both poles
are connected (2 per sister chromatid)
--> Oscillation to pull sister chromatids to the middle until aligned
Metaphase
- Sister chromatids are aligned in the middle of the cell...
--> Metaphase plate forms, cohesin is cut by separase to stop cohesion, resolution of
the metaphase/anaphase checkpoint, and sister chromatids are no longer attached!
Anaphase A
- Initial separation of chromosomes to poles...
--> Dynein pulls chromosomes towards periphery of the cell while Kinesin-13 is depolymerizing
MTs --> Chromosomes are pulled right up against spindle poles
Anaphase B
- Further separation of chromosomes by moving poles...
--> Elongates the cell!
MTs (Anaphase B)
1. Kinetochore MT --> MT attached to chromosomes and poles - (Spindles)
2. Astral MT --> MT attached to outside of poles and plasma membrane - (Dynein glued to
the cell cortex pulls poles towards the periphery of the cell)
3. Nonkinetochore MT --> MT attached to inside of poles moving towards the middle of the
cell - (Kinesin with 4 heads pushes force to separate the poles)
Telophase
- Anti-prophase...
--> Nuclear envelope reforms, chromosomes decondense, MTs rearrange
Cytokinesis
