[Cell-biology] Re: Questions on mitosis

[Perplexed in Peoria]

"Bob" <bbx107.XYZ at excite.XYZ.com> wrote in message news:b3tmg299q3egv9qsrnj8dedfgvu46ebgfi at 4ax.com...
> On 14 Sep 2006 23:03:53 -0700, henry at microtechnonstop.com wrote:
>
> >When it is time for a cell to divide (how does it know when?), part of
> >the work involved is to duplicate its DNA (effectively, copying its
> >nucleus first?). My question is regarding the sudden (?) hefty need for
> >building blocks (deoxyribose, phosphate, purines and pyrimidines),
> >where do they come from?

Well, deoxynucleotides aren't built from scratch as you seem to suggest.
Instead, some of the 'ordinary' RNA nucleotides get converted to DNA
nucleotides.  Just one or two enzymatic steps that need to be 'turned on'
at the right time.  And Bob's response addresses the timing.

> >How does the cell summon their timely
> >presence? What is the "duplication rate," is it known how much time the
> >cell needs to complete a second nucleus?
> >
> >Is this known to any degree at all? What websites would you recommend
> >for details?
>
>
> It is rather well known -- so much that you are likely to be
> overwhelmed.
>
> Start with a simple view of the cell cycle. S phase is for DNA
> synthesis, M phase is for mitosis (the cell division per se). In
> between are two gaps, called G1 and G2.
>
> There are myriad signals to get it all right.
>
> You might google on
> "cell cycle"
> or perhaps
> "cell cycle" "s phase"
> or such.
>
> Or try the Nobel prize site for the recent prize to Lee Hartwell
> (etc), on working this out.
>
> bob