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January 1, 2009 02:05why does life need water?why do all living organisms need water - a molecule that is rarely metabolized ? |
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Hello
(I don't know why the forum adds _underscores_ every time I write "meta")
Water is not rarely metabolised, it is not metabolised at all; water is not a food molecule and is not broken down to release the energy inside it, like proteins are. :blush:
Water is a unique solvent. In life, it provides the medium in which things happen - the optimal place for the chemical reactions of life to take place. Water is the perfect environment that keeps everything swimming happily - from the smallest molecules and all the way up to DNA and enzymes - so that they can interact with each other. In water, everything dissolves happily and rapidly.
You can think of a cell as a container of a chemical soup. In your body, you can find such specialised micro-environments where chemical reactions take place. In fact, your entire body is a tremendous array of chemical reactions. And in these reactions, water is what we call the solvent, an environment where all these chemicals can interact.
Thanks to water, animals can have blood, the solution that carries oxygen and nutrients to the body. The cells and tissues that receive those nutrients are also microscopic sacks of water.
Water molecules interact with each other and other molecules through what is called a hydrogen bond - a weak chemical interaction. The nature of that bond accounts for the behaviour of water, and its uniqueness.
FB
I think you make a great point about water's role as a solvent. I just wanted to add in one of the chemical reactions that water is involved in. Water molecules are split into hydrogen and oxygen to release electrons that are used in the light reactions of photosynthesis. Even though photosynthesis is not essential for all life, it is essential for most eukaryotic life.