Telomerase

Unterholzner Martin h9540395 at edv1.boku.ac.at
Tue Jul 22 08:08:40 EST 2003


"Bev A. Kupf" <bevakupf at ebv.mimnet.northwestern.edu> wrote in message > 
> I think you have that backwards.  The leading strand (i.e. the 
> strand that ends in a 3' hydroxyl, also referred to as the G+T
> telomeric strand) makes use of telomerase to extend the telomeric
> repeats.
> 
> The lagging strand is synthesized either by G-tetrad formation 
> followed by self-priming, or making use of primase/pol-alpha to
> synthesize RNA primers that are extended by pol-delta, followed 
> by MF1 removal of the RNA primers and subsequent ligation of the 
> Okazaki fragments.
> 
> As far as I can tell, there is no consensus as to whether lagging
> strand synthesis occurs by self-priming, or via conventional
> lagging strand synthesis.
> 
> For a reference see:
> Genes VII (pages 562-564).
> 
> Bev


Does the replication always start from the same end of the chromosome
or is this facultative? For example: I have one chromosom with a dna
douple helix:

5'-------------------3'
3'-------------------5'
There are 2 posibilities to start the replication. Once from left to
right or from right to left. From this decision dipends also which one
is the leading or the lagging strand. My question is, if the origin of
replication(ori)also gives  the directions of the replication or can
the direction change from time to time? If the direction can change,
the terminology of leading and lagging strand is vague. Propably that
was  the confusing factor.

Martin Unterholzner



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