Chemical evolution

[pankaaj]

Why nature has choose Carbon instead of Sillicon to form biomolecules??

[2810712]

Let's think...
I'm trying to clear the question to myself---


Why are C , H, O, P ,N ,S etc. are present in living things in their specefic percentage of structural and functional contribution???
Why tetravalents...as central atoms??? why not mono, di, tri penta or .....???
Why only covalent compounds??? Why the Earth???
Somany q.s
Life requires some stability threshold [and some privacy... ]to exist... to have progeny...to have some control on its processes.
see, availability of that element in usable form, environment [ favouring 'useful' reactions and providing stability threshold,Energy available and its form
tell if certain option is the fittest or not.

So, at a given time at the given place in the universe, these factors change so it can't be sayed that C is best choice for life. The best choise varies as all these [ place , time etc.] vary.The best choice must atleast remain best till life gets evolved with it.

But there can be a best choice for a given place and at the given time.
For earth it was carbon as central atom.

It might not have been a race between individuals with Si- biomolecules and C-biomolecules, because see at a time evolution of two living systems [ one with Si and one with C] is not impossible but rarely possible.

We should not forget that life may have arrived from some asteroid , this adds to these somany possibilities.

we should check some books on ChemEvo.

By the way, why covalent compounds are only selected??? Seems also to be similar question.for earth has alot of water so dissociation of ionic compounds will not keep any privacy, threshold stability is not provided.
But don't think that life can't exist with ionic, vander Wal's etc. forces for they may be ''fittest'' option somewhere else and at some time. We just have to find fittest time and fittest location.

Phew.....

THANKS FOR SUCH A NICE QUESTION!!!
After we all get done with the answer of this question we get a PhD i hope...

Shrei

[pankaaj]

The simplest thing I read about this Que. is-
1) Elemental Si don't occur in free state in Nature!
2) It is always present in combined state in the form of sillicates & other compounds!
3) While c is present in free state in bulk ( so to say)
4) So it is always energitically favourable to use C instead of Si !
So it is always important to make bonds instead breaking them! RIGHT!