FOM 7.4.1 Flashcards
What are the phases of mitosis?
Prophase, Metaphase, Anaphase, Telophase
What happens in early/late prophase?
Early: condensation of replicated chromosomes Late: MT have self-assembled and replicated centrosomes move apart
What happens in prometaphase?
Break down of nuclear envelope, allowing spindle MT to interact w/ condensed chromosomes
What happens in metaphase?
Chromosomes are aligned along equator forming metaphase plate and bipolar spindle is clear
What happens in early/late anaphase?
Early: cohesins degrade, sister chromatids seperate, daughter chromosome move toward poles Late: Spindle poles move farther apart, enhancing separation of chromosomes
What happens in telophase?
Formation of daughter nuclei
What type of tubulin helps organize MT at the centrosome?
Gamma
Describe the polymerization of tubulin?
Very dynamic (standard life span is 33s)
What are the three types of MT involved with mitosis? Their function?
Overlap MT: provide spindle structure and interacts w/ opposing overlap MT Astral MT: anchors the centrosome Kinetochore MT: Bind at kinetochore/centromere
What is know as the MT organizing center? What is it surrounded by?
Centrosome, pericentriolar material
What is the mother centrosome? Where is found?
The centrosome that is present during all phases of the cell cycle, helps organize primary cilia. It is found in cytoplasm attached or close to the nucleus during interphase.
When is the centrosome duplicated?
S phase (Just like the DNA, Miles)
What tightly regulates centrosome function?
Proteins of the pericentriolar matrix
Which protein is responsible for causing mitotic arrest or cell death if polarity of the centrosome is abnormal?
p53
What are two important facts about the kinetochore in relation to its function during mitosis?
Stabilizes plus end of MT, binds to centromere
What portion of the kinetochore is responsible for stabilization of the + end of the MT?
Dam Complex
What is the special type of histone protein that is recognized by the kinetochore influencing its attachment to the centromere?
CENPA
What are three mitotic kinases that control spindle formation? Their location?
Aurora Kinase A (centrosome), Polo Like Kinase (centrosome and kinetochore), Aurora Kinase B (kinetochore/spindle midzone)
When is the Spindle Assembly Checkpoint (SAC) turned on?
SAC is turned on until there is proper attachment to both kinetochores, one on each side. SAC signals to MCC to stop progression until spindle is properly assembled.
What does APC stand for?
Anaphase Promoting Complex
What inhibits the APC?
The Mitotic Checkpoint Complex (MCC), which is composed of BUBR1 and BUB3
What sequentially degrades cyclins and mitotic kinases to push the cell through mitosis?
Anaphase Promoting Complex (APC)
What are responsible for provided the force to pull apart the spindle?
Kinesin, Dynein, and Myosin (just a reminder: they use ATP hydrolysis to provide energy to walk)
What is surrounds the midbody? (The midbody is the middle area in b/t the two centrosomes that have the chromosome towards them)
An actin ring
What regulates the actin contractile ring that pinches the two daughter cells apart?
Aurora B and PLK
What is the molecular function of Taxol (from the Pacific Yew)? Why is this good as a first-line therapy against cancer?
Stabilize tubulin; by not allowing for the destabilization, spindles start getting stuck preventing formation of a functional spindle that induces cell death due to prolonged spindle assembly checkpoint.
Look at these two slides to better understand how the checkpoints interact with one another.
What is the process of the spindle assembly checkpoint?
When there is an unattached kinetochore, MAD2 binds to the open region. MAD2 then binds to CDC20 which is part of SAC. The other part of SAC is the APC. MAD2 and CD20 binding to SAC leads to recruitment of the MCC (BubR1 and Bub3). Which will cause dissociation of MAD2 from the SAC. The MCC binding will cause the APC to be inhibited and cannot carry out normal functions of degrading cyclin B and securin. When the there is proper alignment of the chromosones MAD2 will not interact with CD20, and eventually MCC will dissociate from APC and the APC will now be active and can degrade its proper targets
