3.2 Cell Cycle 2 Flashcards
What does condensin do?
Chromosome condensation and resolution
What triggers assembly of mitotic spindle?
M-cdk
At what stage to microtubules get organized?
mitosis stage
What are the 3 types of microtubules?
kinetochore, interpolar and astral
What do kinetochore microtubules do?
attach each chromosome to spindle pole
What do interpolar microtubules do?
Hold two halves of spindle together
What do astral microtubules do?
interact with cell cortex
what end of kinetochore microtubules are attached to sister chromatid pairs at large protein structures called kinetochores?
Plus end
What ends of interpolar microtubules from one pole interact with plus ends from other poles?
plus ends
Astral microtubules radiate outward from te poles and contact the cell cortex to help with what?
Help to position the spindle in the cell
All spindle microtubules bind to what?
Centrosome
Microtubules are nucleated from what?
MTOC
Microtubules grow outward from the MTOC from what end?
Plus end
What are the two motor proteins?
Dyneins and kinesins
What are two things about Dyneins?
Tend to move to the center of the cell and is a minus end directed microtubule motor
What are 4 things about kinesins?
Tend to move to periphery, walk toward plus ends, has 2 globular heads and elongated coil coil tails, plays role in chromosome separation.
what proteins does assembly and function of mitotic spindle depend on?
Kinesins and dyneins
What are the 4 classes of motor proteins involved in spindle assembly and function?
Kinesin 5, Kinesin 14, Kinesin-4,10, Dynein
What is Kinesin-5?
two motor domains that interact with plus end of anti parallel microtubule that force them past each other to push the spindle poles (centrosomes) apart.
What is the movement of Kinesin-5?
Toward plus end, force centrosomes apart
What is Kinesin 14?
Minus directed motor with a single motor domain.
What is the movement of Kinesin 14?
Toward Minus end, pulls poles together.
How are Kinesin 5 and 14 related?
Kinesin 5 pushes poles apart while kinesin 14 is pulling poles together.
What is Kinesin 4,10?
Chromokinesins, plus directed motors
What is the movement of kinesin 4,10?
Toward plus end, push attached chromosomes away from pole.
What are Dyneins?
Minus end directed motors, link plus ends of astral microtubules to actin skeleton at cell cortex
What is the movement of dyneins?
Toward minus end of microtubules, pulls the spindle poles away from each other
What are kinetochores responsible for?
attachment of spindle to chromosomes
What attaches to the kinetochore?
microtubules
True or False? There is an exposed open end for addition and removal of tubulin subunits on kinetochores
True
Removal of tubulin subunits leads to what on the kinetochore?
leads to force pulling
What are the 3 forces in chromosome movement?
Depolymerization, microtubule flux, polar ejection force
what does Depolymerization movement do?
Pulls the kinetochore and chromosome toward the spindle pole
What happens with microtubule flux?
Treadmilling. Microtubules are moved toward spindle poles while being dismantles at minus ends
What motor is involved in polar ejection force?
Kinesin 4,10.
What results from polar ejection force?
push pull phenomenon
What is the first step in the cell cycle entry into S-Phase I?
Mitogens active the Ras-MAPK pathway by binding to receptor.
What is the second step in the cell cycle entry into S-Phase I?
Ras causes activation of MAP kinase cascade
What is the third step in the cell cycle entry into S-Phase I?
Turns on gene regulatory protein Myc.
What is the fourth step in the cell cycle entry into S-Phase I?
Myc promotes entry into cell cycle by increasing expression of G1 cyclins. Get active G1 cdk-cyclin
What is the 5th step in the cell cycle entry into S-Phase I?
G1 cdk cyclin activates EF2
What is the 6th step in the cell cycle entry into S-Phase I?
E2F binds to promoters of S cyclin genes. Leads to DNA transcription.
What is the 7th step in the cell cycle entry into S-Phase I?
Enter into S phase of cell cycle and DNA sunthesis begins (duplication of chromosomes).
How can the cell control mitogens that activate the Ras-MAPK pathway?
with a protein called Rb
Whats the first step that allows Rb to interfere with the Ras-MAPK pathway?
E2F protein is inhibited by Rb protein
Whats the 2nd step that allows Rb to interfere with the Ras-MAPK pathway
shuts down entry into S phase
Whats the 3rd step that allows Rb to interfere with the Ras-MAPK pathway
Active G1-cdk P’s Rb to reduce binding to E2F
Whats the 4th step that allows Rb to interfere with the Ras-MAPK pathway
Now can enter into cell cycle and Rb protein inactivated
What happens if the RB protein does not work?
Retinoblastoma.
What are the first three steps in Cancer and the cell cycle-ATM/ATR?
- DNA damage blocks cell division. 2. Cell cycle cant proceed with DNA damage. 3. ATM and ATR protein kinases activated
What is the 4th step in Cancer and the cell cycle-ATM/ATR?
ATM and ATR kinases P Chk1 and Chk2 proteins
What is the 5th step in Cancer and the cell cycle-ATM/ATR?
p53 is P by Chk1/Chk2 and stimulates transcription of p21
What is the 6th step in Cancer and the cell cycle-ATM/ATR?
P21 CKI binds to G1/S cdk and S-Cdk to inhibit activity. No cell division-DamagedDNA- must repair
What happens when the ATM/ATR system is not working?
AT and can lead to cancer as theres no DNA repair.
What is one thing to know when someone is diagnosed with AT?
No x-rays because when DNA damage is bad p53 causes apoptosis.