Chemical and Physical Properties Of Water

Water is an excellent solvent because the water molecules are attracted to ions and polar molecules. Water molecules are attracted to the ions, surround them and separate them so that they dissolve. Due to its ability to dissolve so many molecules it is an important material in transportation in animals and plants.

Cell Membranes

Cell membranes control what enters and leaves a cell, as well as keeping the cell contents together. Much of the membrane is made up of a ‘sea’ of phospholipids with protein molecules ‘floating’ in between the phospholipids, the phospholipids are usually arranged in two layers. The phosphate heads are polar molecules so are water soluble, the lipid tails are non-polar, so not water soluble.

Carbohydrates

Monosaccharides – single sugars that dissolve in water and taste sweet. Has the formula C6H12O6. Glucose and fructose are simple sugars and are isomers, same number of C H O atoms but arranged differently. Fructose has a different shape to glucose and the different shape means it has different properties.

Disaccharides – these form when a condensation reaction joins two monosaccharides. 2 glucose molecules form maltose and two fructose molecules form sucrose.

Polysaccharides – are giant molecules such as glycogen and cellulose, formed when many single sugars undergo condensation reactions.