March 22: World Water day
WORLD WATER DAy
There is an angle crucial to the origin and evolution of life on Earth: 104.5 degrees, the bond angle between two hydrogen atoms and one oxygen atom in a water molecule.
Due to this specific geometry, water is a polar molecule, exhibiting a partial negative charge near the oxygen atom and partial positive charges near the hydrogen atoms. This polarity is central to water’s unique properties. Notably, cohesion between water molecules—enabled by hydrogen bonds—allows water to exist in liquid, gaseous, and solid states on Earth.
Water’s polarity also governs the organization of biological membranes, positioning their polar heads toward aqueous environments and their nonpolar tails inward, forming lipid bilayers and allowing subcellular compartmentalization.
As the universal solvent, water dissolves a wide variety of substances, from salts and proteins with polar surfaces to monosaccharides with polar hydroxyl groups. Additionally, it plays an integral role in maintaining protein structures.
Water also influences DNA’s double helix structure, positioning phosphate groups and pentoses outward while nitrogenous bases remain inside the molecule.
Furthermore, the amount of glycogen stored by organisms is limited by water of hydration.
Critically, water served as the source of electrons and protons necessary for the development of oxygenic photosynthesis, releasing oxygen as a byproduct.
Initially, released oxygen reacted with iron dissolved in Earth’s ancient oceans, forming insoluble iron oxides and creating deposits of iron ore, a key resource fueling the Industrial Revolution. Once marine iron was saturated, oxygen accumulated in the atmosphere, eventually forming the protective ozone layer crucial for terrestrial life.
Water ionizes into H+ and OH- ions, the concentrations of which are foundational to understanding pH and buffer solutions. Additionally, water participates actively in enzyme-catalyzed reactions. Condensation reactions, forming polymers like proteins, nucleic acids, and polysaccharides, involve dehydration and are reversed through hydrolysis reactions mediated by water.
In summary, life as we know it is deeply and intrinsically connected to water, both structurally and metabolically. Therefore, on World Water Day, let us celebrate this extraordinary and essential molecule!
