newbie question about DNA and cells

Jayakumar, R R.Jayakumar at RoswellPark.org
Fri Jan 2 09:56:13 EST 2004


Dear Eric
      That explains your interest.  Pretty interesting, the TSP problem.  I guess you should try evolutionary biology or the developmental biology fields.  Most of them have now specialised into the molecular aspects of it.  But for your information, I guess you cannot always apply the TSP problem parallely to what is happening in the human body.  Most of the specialized cells are not made in one central place and distributed to find their place in the human body.  They GET ALL THE INFORMATION from its mother cell (the classic question of the chicken and the egg follows after that).  Nearly all cell specialization and differentiation happens even before you are born and they are all there in place when you come out to the world.  They just keep dividing and dying (through a very interesting apoptosis mechanisms).  If they dont die and replace themselves, you have cancer.  :-))).  Another piece of interesting info is that in the case of the baby girl, all the eggs she will every produce in her mature life is already in place when she is in the womb.  Pretty interesting uh?
	 Most of the differentiation happens during development of the embryo from a single cellular state to the multicelluar organism that it becomes.  Most of the processes happening in the womb are still not understood.  If they were understood we would not have so many genetic disorders and diseases affecting man.  But since human embryo studies are frowned upon by all and sundry, we may have to wait a long time, before we can learn those processes. Whatever we know comes from the studies of mice, fruitflies etc.  Otherwise we would be able to create life in a Petri dish.  But one day we will learn all that and then it may be possible to do so.  I shudder to think about that day.
      Anyway, you should try out developmental or evolutionary biology.  Dig into classic cell biology too.  A lot of books for you to study.  best of luck.  You can start out with 'Molecular biology of the Cell' by Bruce alberts, Watson, or 'Biochemistry' by Lehninger or the one by voet and voet or the same title by 'Stryer.  There is a immunology book too which I think should be interesting, a book written by Travers.  pretty nice book.  
    best of luck
jai

        

> ----------
> From: 	owner-cellbiol at hgmp.mrc.ac.uk on behalf of Eric Hanson
> Sent: 	January 1, 2004 2:34 AM
> To: 	cellbiol at hgmp.mrc.ac.uk
> Subject: 	Re: newbie question about DNA and cells
> 
> I'm coming to this from an information systems perspective.  The human
> body is arguably the most complicated information system on the
> planet.
> 
> There is a problem in computer scientist called the Traveling Salesman
> Problem (TSP) that is one of the greatest unsolved problems in
> mathematics/comp. sci.  I'm exploring a theory that the human body
> seems to solve this problem.
> 
> The traveling salesman problem states that a traveling salesman wants
> to visit for example the 50 capital cities of the US starting and
> ending in Salem, and travel the shortest route between them all. 
> Where does it go first from Salem?  Where after that?  Finding the
> optimal solution by trying all possible combinations is a simple
> algorighm but the number of solutions increases exponentially and
> after just a few cities it becomes computationally unfeasible to use
> this method.  People trying to "solve" the traveling salesman problem
> are looking for an algorithm that finds the optimal solution much
> faster than the brute force method, namely in polynomial time.
> 
> To rephrase, the TSP deals with a problem where there are many nodes
> (cells) in a graph (body) and in order for a single node to know who
> its neighbors are as indicated by the shortest route through all
> paths, it has to have a bird's eye view of the entire graph and know
> the shortest route through it.  This seems to parallel what the human> 
> body does because for a single cell to know what piece of a liver it
> should be it needs to know its place in the entire liver and the
> entire body for that matter, or at least that's the theory I'm
> exploring.
> 
> So a cell divides and the new cell starts expressing different genes,
> but maybe someone can answer me this.  _Where_ does it get the
> information to know which genes to express?  Is it from the cell it
> divided from, or from the extracellular cues or ...?  If the answer is
> too complicated or if it's just not known yet, is there a term for
> this area of study or you could point me more specifically towards
> something?
> 
> Thanks,
> Eric
> 
> R.Jayakumar at RoswellPark.org ("Jayakumar, R") wrote in message news:<97101976F8A044468CA74FE11883B90E020489A0 at VISTA.roswellpark.org>...
> > Even though all cells contain the same set of genes (genes are pieces of 
> > DNA which expresses RNA which translates into proteins), not all genes 
> > are expressed in all cells.  Through a complicated system of gene 
> > regulatory elements very early in the cell differentiation pathway, 
> > cells get specialised and channelled into particular duties.  Hence only 
> > particular genes necessary for the specific function of each cell type 
> > (which comprises a specialized tissue like the muscle or tonail) are 
> > turned on in that cell while the other genes are more or less silent or 
> > silenced.  
> >      If you need to know more about that, you have years of molecular 
> > biology to learn.  ACtually most of molecular biology and cell biology 
> > deals exactly with what you just asked. :-)))  If everybody knew exactly 
> > how cells function, we wouldn't have cancer or a host of other medical 
> > diseases anymore.  But we are working towards it. :-))
> 
> 
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