MadSci Network: Biochemistry

Re: Life requires water, why?

Date: Fri Dec 8 13:07:48 2000
Posted By: Andrew D. Brabban, Faculty, Biology, The Evergreen State College
Area of science: Biochemistry
ID: 973229143.Bc

Water is the most abundant chemical in all living organisms. It is such an 
intrinsic part, that as  you are well aware, it is the first thing we talk 
about when looking for life on other planets. So why is it needed and what 

You are right to suggest it acts as a solvent. A cell is like a huge (I 
know we consider it minuscule but in terms of the size of molecules it is 
huge) chemical reactor but with all the reactions inter-inked to create a 
massive reaction web. The products of one reaction are used in another, 
and the products from that reaction in another. It is therefore important 
that the chemicals be able to be solution and as such diffuse so that they 
collide with other reactants and enzymes. 

The 2nd component of the need for water in reactions is the nature of the 
chemicals involved and the reactions themselves. In your question you 
comment on RNA and the need for organic molecules of life to be in an 
aqueous solution. If we look at most of the organic molecules of life they 
are water soluble, but this is a bit like a chicken and egg story. They 
are because water was the solvent or was it the other way round. Well 
water was the only major solvent available at the "dawn of life" so 
necessity was filled. Another consideration is that all of the 
macromolecules of life use water in their synthesis and degradation. 
Proteins, Lipids and Carbohydrates monomers are all polymerised into 
macromolecules by dehydration reactions (the removal of water) and 
degraded by hydrolysis reactions (water in). So again we can see that 
water is an intricate part of life.

We could continue to discuss this and bring in more examples but I think 
you can see the train f thought here, One final answer however is yes it 
does have to be liquid. Why? Well think about the above, it needs to allow 
diffusion and be able to be a reactant. Solid water does not fulfil these 
2 criteria.

Current Queue | Current Queue for Biochemistry | Biochemistry archives

Try the links in the MadSci Library for more information on Biochemistry.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-2000. All rights reserved.