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In a delayed S phase, does DNA synthesis still occur?

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In a delayed S phase, does DNA synthesis still occur?

Postby face » Wed Apr 09, 2008 10:12 am

Specifically, if the delayed S phase is caused by damage to DNA, does this mean that during the delayed part of the S phase there is no DNA synthesis whatsoever untill the DNA is repaired? I'm hearing differing accounts of this. Some text says DNA synthesis is attenuated when this happens, others, like wikipedia, say DNA synthesis happens before repair occurs:

"DNA repair is initiated following the completion of replication"
http://en.wikipedia.org/wiki/S_phase

If the answer to this question is yes, are there any cases where S phase is delayed due to DNA damage, but DNA synthesis still occurs during the delayed peroid?
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Re: In a delayed S phase, does DNA synthesis still occur?

Postby noy k » Thu Apr 17, 2008 4:30 am

In the S phase, a series of sensors would detect DNA damage or any abnormalities and trigger a response that temporarily arrest further celll cycle.

The cell would use the delay to repair the the damage rather than continuing to the next phase. If the DNA is damaged beyond repair, the checkpoint mechanism would transmit a signal that leads to the death of the potentially hazardous cell.

The DNA repair referred to in wikipedia would refer to the error in replication process during S phase.
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Postby Ultrashogun » Wed Apr 30, 2008 8:30 am

DNA repair after replication always happens, but if the cell delays the S phase due to DNA damage it will repair it first, then continue. Look for p53, it is a major element in this 'delay or die' decision.
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