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Flashcards in exam 3 - cell cycle 2 Deck (22)
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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
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
  • Anaphase B
    • seperation of spindle poles themselves
      • by kinesin-5 motor proteins ; (also dynein pulls pole apart)
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
17
Q

What is retinalblastoma?

A
  • Due to the lack of Rb protein
  • Rb is a tumor supressor and inhibits cell division
  • Loss of copies of both Rb genes leads to cell and tumor proliferation of retina
18
Q

WHat are sime example cancer genes?

A
  • Many Mitogen activating genes are as cencer -promotoing genes or oncogenes identified
  • RAS is mutated in 30% of cancers
  • p53 mutations occur in 50% humans cancers
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
20
Q
A
21
Q

What three mechanisms controll cell growth?

A
  1. rate of cell dvision determined by extracellular factors leading to cell
  2. cell growth and division controlled seperately by growth factors and mitogens
  3. cell growth and dvision both stimulated by extracellular factor
22
Q

What is myostatin ?

A

Inhibts muscle cell growth