Friday, January 9, 2009

why water

It has been raining lately and this made me think of water. In my Nov 7, 2008 post (water world), I mentioned that water is the most abundant component of cells. In that post, I corrected a common misconception, that water is a universal solvent. It is not! It's just a very good solvent but it definitely is not a universal solvent!

In today's post, I will try to answer why water is the most abundant component of cells. Well, the reasons are because of its physical and chemical properties.

What are these properties? Among its important physical properties are: high specific heat, high heat of vaporization, high heat of fusion, high surface tension. Its dipole moment as well as its ability to form hydrogen bonds are its important chemical properties.

So what is so important about these physical and chemical properties? Well, because of its physical properties, water remains as liquid in a large range of temperature. It takes a lot of energy before water can be converted to vapor (high heat of vaporization) or solid (high heat of fusion). It can also absorb a lot of heat before its temperature changes even one degree centigrade (high specific heat). Thus, water does not easily get heated nor cold and this stability is very important for cells. If water is easily converted to vapor or to ice, can you imagine what would happen to our cells and to us if we find ourselves in very high during summer or very low temperatures during winter?

The high surface tension of water is also very important. This causes water molecules to create a film on surfaces and this is very important especially in maintaining breathing surfaces of our lungs.

The chemical properties of water are of course the reasons why water is a very good solvent. Their chemical properties allow them to  participate in many biological processes that keep us alive.

So there you are, those are the reasons why water is the most abundant component of cells.

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