Cell Cycle Flashcards
G1, S, G2, M Phases
Grow, Replicate DNA, Grow, Segregate DNA, Divide Cytoplasm
Interphase
G1, S, G2
Mitosis
Segregate DNA. Nuclear and cytoplasmic division. 5 distinct phases.
Cytokinesis
Divide cytoplasm in two. Cytoplasm and organelle segregation + membrane scission.
Prophase, Prometaphase, Metaphase, Anaphase, Telophase
(P)Parent cell chromosomes — which were duplicated during S phase — condense and become thousands of times more compact than they were during interphase. (P)Nuclear envelope breaks down and spindles attach to chromosomes. (M)Chromosomes line up at equator/plate (A)Sister chromatids are pulled apart. (T)Chromatids move to opposite ends and re-establish nuclear envelope.
G1/S Checkpoint
Start checkpoint. Enter cell cycle and proceed to S phase. Is environment favorable?
G2/M Checkpoint
Enter Mitosis. Is all DNA replicated correctly and is environment favorable?
Spindle Assembly Checkpoint
Are all chromosomes attached to the spindle correctly?
Metaphase-to-Anaphase Transition
Trigger anaphase and proceed to cytokinesis.
Cyclin
Accumulate in mitosis. Goes up in mitosis, down in interphase.
Cdk (Cdc2 in Fission Yeast)
Cyclin dependent kinase
CyclinB/Cdk Complex = M-Cdk (Promotes M Phase)
Binding of M-Cyclin to Cdk activates the kinase (Cdk).
CyclinA/Cdk Complex = S-Cdk (Promotes S Phase)
Binding of S-Cyclin to Cdk activates the kinase (Cdk).
CAK- Cdk Activating Kinase
Causes structural change that activates the cyclin-CDK complex by phosphorylating the active site of Cdk. Cyclin-Cdk complex is now fully active.
Wee1
Mutant yeast that prematurely enters G2/M transition and goes through mitosis. Wee1 encodes a kinase that inhibits M-Cdk (M-Cdk usually drives forward mitosis).
Cdc25
Full activation of M-Cdk requires removal of the Wee1 inhibitory phosphate by Cdc25 phosphatase.
APC/C (Anaphase Promoting Complex) - Different from APC involved in Wnt/Beta-Catenin Signaling
A ubiquitin ligase complex that targets M-cyclin for proteasomal degradation. Initiates chromatid separation.
Cdc20
Cdk activates Cdc20 which is an activating subunit. It interacts with inactive APC/C to make active APC/C which will add ubiquitin and E1/E2 ubiquitylation enzymes that leave a polyubiquitin chain on M-cyclin that directs it for degradation by proteasome. Activated APC/C will also ubiquilize securing so that Separase is active.
Securin
Prevents separase from doing its job; it inhibits separase.
Separase
Binds to cohesions and cleaves them. Cohesions dissociate so chromatids can then separate.
Cohesin
Ring like proteins that hold together sister chromatids.
Ubiquitination
Mark for degradation in proteasome.
Astral Microtubules
Brace against membrane.
Kinetochore Microtubules
Bind to kinetochore
Interpolar Microtubules
Lie adjacent to microtubules from opposite pole.
Poleward Flux
The translocation of spindle microtubules toward spindle poles coupled to the depolymerization of their minus-ends and polymerization of plus-end. This is why speckles are seen moving further and further away from middle. Can shorten spindle microtubules during anaphase A, pulling chromatids to centrosomes. Anaphase B is motor driven, like Kinesin 5 pushing poles apart.
Speckle Microscopy
Monitor microtubule dynamics. Speckles are almost like dye. We see that as time progresses on kymograph, the speckles move further away from the center. The dye/speckles originate from center of chromosomes.
