exam 3 - cell cycle 2 Flashcards
1
Q
What is condensin
A
- Chromosome condensation (compacting) and resolution (sister chromatids) become distinctly seperate units
- Prevents breaks from forming if chromosomes were left tangled mass and pulled apart
- just reorganizes sister chromatids in smaller compacts forms
- 5 subunit protein complex
- 2 SMC subunits
- forms ring like structure and uses ATP to promote compaction and resolution
2
Q
.What are the three classes of microtubles involved in the mitotic spindle
A
- MItotic Spindle “centrosome”
- bipolar array of microtuble proteins that pull sister chromatids apart at anaphase.
- Triggered by M-Cyclin-CDK complex
- microtubles nucleated from a specfic location called microtuble organizing center (MTOC) on centrosome
- Microtubules
- Kinetochore
- Attach each chromosome to spindle pole
- interpolar
- hold two cells havles together
- Astral
- interacts with cell cortex
- Kinetochore
3
Q
what is the structure and fuction of the kinetochore
A
- plus end of kinetochore microtubules are attached to sister chromatid pairs at large proteins structures called kinetochores located at the centromere of each sister chromatide.
4
Q
How does an interaction with a interpolar microtubule take place
A
- The plus end of interpolar microtubles comming from one poe interact with plus ends form the other pole
- poles refering their own respective cell
5
Q
what is the function of astral?
A
Radiate outward from the poles and contact the cell cortex helping to position the spindle in the cell
6
Q
What is the role of kinesin-5?
A
- kinesin-5
- two motor domains that interact with plus end of antiparallel microtuble
- move these two antiparallel microubles past each other to force or push the spindle poles (centrosomes) apart
- moves centrom\somes apart
7
Q
What is kinesin 14?
A
- Kinesin-14
- Minus oriented directed mtor with a single motor domain
- mobement pulls the poles together
- so whole kinesisn 5 pushes poles apart while kinesin 14 is pushing poles together
- if no kinessin 5 then spindle falls apart
8
Q
What is Kinessin-4,10?
A
- Kinesin 4,10
- also called chromokinesins - plus directed mtors
- movement is toward the plus end and pushes attached chromsomes aaway from the pole
9
Q
What is the role of Dynein?
A
- Dynein
- Minus end directed mtors
- links plus end of astral microtubles to actin skeleton at the cell cortex
- by moving toward the mius end of microtubles, the dynein mtors pull spindle poles away form each other
10
Q
What are kinetochores?
A
- responsible for attachment of spindle to chromosomes.
- spindle microtubles are attached to each sister chromatid at the kinetochore
- NDC80
- A complex where multiple microtubles are attached. AN anchoring protein
- There is an exposed end for addition and removal of tublin subunits
- removal = a pulling force on kinetochore = movement of chromosome to pole of cell
- Binding to kinetochore
- bipolar attachment
- sister chromatids must attach opposite poles of mitotic spindle (bi orientation)
- just esential attachement to each pole
- formation of unstable poles not allow
- detect by kinetochore via tension
11
Q
What are the three forces involved in chromosome movement?
A
- depolymerization
- major force pulls the kietochore and chromsome toward the spindle pole
- depolymerization of the plus end of the microtublule drives the pulling of the kinetochore polward
- MIcrotuble flux
- microtubles are moved toward spinlde poles while being dismantled at minus ends
- tublin added at plus end while being removed at minus end (interpolar)
- polar ejection force
- Kinesin - 4,10 motors on chromosomes interact with microtubles and transport chroosmes from poles results in push pull
12
Q
What are the different parts of Anaphase?
A
- Anaphase A
- chromosomes move apart
- due to spindle microtuble depolymerization at kinetochore
- chromosomes move apart
- Anaphase B
- seperation of spindle poles themselves
- by kinesin-5 motor proteins ; (also dynein pulls pole apart)
- seperation of spindle poles themselves
13
Q
How does ATM relate to cell growth (CHk1, Chk2, P53, p21 CKI)
A
14
Q
What is Ataxia Telangiectasia (AT)?
A
- ATM protein is defective and cannot fix DNA damage
- Increased chance of developing cancer
- No DNA Repair
- Can be caused by Xrays
- ATM senses DNA damage
- Major substrates are Chk1 and Chk2
- activate p53
- p53 causes cell arrest and DNA repair occurs
- if damage is realy Bad then p53 causes Apoptosis
15
Q
What are the Controls of cell division?
A
- CLASS 1: MITOGENS
- stimulate cell divisions by triggering G1/S-Cdk activity
- CLASS 2 GROWTH FACTORS
- stimulate cell growth
- CLASS 3 SURIVIAL FACTORS
- Suppress form of programmed cell death known as apooptosis
16
Q
How does retinal blastoma relate to cell growth
A
19
Q
What is cell growth and how does it relate to PI 3 kinase
A
- Cell growth:
- under steady sate conditions, cells double their mass and then divide to generate two daughter cells of the same size of parental cells
- in animals governed both by cell growth and cell divisions factors that are dependent on extracellular signals ( like growth factors and mitogens)
- PI-3 kinase pathway
- most important growth signaling pathway
- PI-3 kinase adds ATP to inositol phospholipids
- activates TOR (target of Rapamycin) which activates many factors for cell growth
21
Q
What three mechanisms controll cell growth?
A
- rate of cell dvision determined by extracellular factors leading to cell
- cell growth and division controlled seperately by growth factors and mitogens
- cell growth and dvision both stimulated by extracellular factor
