sturge_weber
Forum Guru
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well it inhibits the cyclin d kinase, inhibition of p53, will allow lots of cyclin d kinas e to be present, and cyclin d kinase will inhibit the rb gene, well none choices match
but i think e is the closest
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| drk1980
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i'll try B!
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| sturge_weber
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why drk
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| reet
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B
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| sturge_weber
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can u guys explain why re u choosing b, i think i have a mind block, i am not able to answer any questions on th forum o god....
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| roopashri
Forum Elite
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p53 normally inhibits active cyclin D/cdk complex, which will prevent phosphorylation of Rb protein and hence keeps cell in G1 phase
inactivation of p53 will make active cycilD/cdk complex to phosporylate Rb protein, so cells go into S phase..
now coming to choices given..
A ... is not correct cells will pass from G1 to S
B... wrong, cyclin D is syn in G1 phase
C... cdk is activated
D... mitotic rate is increased
E... can be right
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| skyhigh
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try again, anything else?
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| drk1980
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sturge, ur doing a good job. u hv ur basics straight. this ws actually just a guess for me....from UR expln! if its correc ti'll attempt to explain why..
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| reet
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basically p53 --inhibits G1 to S phase....
cyclin D + inactive CDKinase---- active complexlex,,,which normally inhibited by P53.
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| skyhigh
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sorry, there is a mistake in the question, (i copied it word for word)
ans is given as a, but the unrestricted passage should be from G1-S phase, like roopashri said, or from G2-M phase.
NOT, G2-S phase.
sturge's thinking was right that inactivation of the p53 will allow more cyclin D kinase to be made.
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| Doc2378
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Good explanation there Roopa...hey Sturge...you are doing fine, actually better than fine...you are far better than me at these questions
I'd go with E too...seems the closest one..
The way I understand it is:
Normally, Rb prevents cells from going from G1 -> S phase
Cyclin D/Cdk complex phosphorylates Rb and deactivates it so the cell can go from G1 -> S phase
In case of a DNA damage p53 blocks the Cyclin D/Cdk complex from phosphorylating Rb so the cell gets arrested in G1
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| Doc2378
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Aha'...I thought so too...thanks for letting us know skyhigh...
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| drk1980
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skyhigh, thanks! good Q.
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| skyhigh
Forum Guru
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BTW, the mechanism for Rb suppressor is different.
It prevents cell from entering S phase by binding to the elongation or transcription factor(E2F).
If not bound to E2F, then cell can go from G1-S phase.
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| malinda
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could anyone explain what phase of cell cycle has enzyme synthesis?
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| ManuNastai
Transilvanian..
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in the G1 phase the cell gathers all the materials needed
in the S phase all the sinthesis is done (proteins- enzymes-, nucleic acid etc)
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| mjl1717
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Lets beat p53 and cell cycle into the ground: just a few points : p53 known as the "guardian of the cell" it is an anti oncogene inhibiting cyclin D an E between G1 and S phases as stated above. G1 is where RNA, lipod, and carbo is synthesized! {this action is at the G1 checkpoint!!!!} [this futile cycle is G1>S>G2>M, futile means this goes on and on. supposedly ATP synthesis occurs in G2]
Edited by mjl1717 on 03/12/06 - 02:04 PM
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| ralux
Forum Senior
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can u pls tell me where i can read info about the cell cycle and the supressor genes.I read only Kaplan and there is no info there about this.Thanks
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| tolito
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robbins.
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