Principles of Biochemistry Volume 1 - A. Lehninger 1985

Biomolecules
Water
Adaptation of living organisms to the aqueous environment

Living organisms have successfully adapted to the aquatic environment and even acquired The ability to harness the unusual properties of Water. Due to its high specific heat capacity, water acts as a “thermal buffer” within Cells, helping to maintain a relatively constant body Temperature despite fluctuations in ambient air temperature. The high heat of vaporization of water is utilized by certain vertebrates to protect the body from overheating through evaporative cooling via sweat. The strong cohesion of molecules in liquid water, driven by intermolecular Hydrogen Bonds, ensures the efficient transport of dissolved nutrients from roots to leaves in plants during Transpiration. Even the fact that ice has a lower density than liquid water and therefore floats in it has significant biological implications for the life cycles of aquatic organisms. However, the most critical aspect for living organisms is that many essential biological properties of macromolecules, particularly Proteins and Nucleic Acids, stem from their interactions with surrounding water molecules. As we will see below, the specific three-dimensional structures of proteins, which dictate their biological activity, are sustained by The properties of water. Even such a vital process as METABOLISM/36.html">DNA Replication depends entirely on the properties of water.