How the Molecular Structure of Carbohydrates, Proteins and Lipids affect their function in living things.
Living cells contain many small molecules such as water and inorganic ions like nitrogen. They also contain a vast number of larger molecules, called macromolecules that are built from smaller, simple molecules. They are also known as organic molecules because they contain carbon. All living things on earth are carbon based life-forms because the element can bond with itself repeatedly to form an infinite variety of molecules.
Carbohydrates are organic molecules, including all sugars and starch, and contain three elements: carbon, hydrogen and oxygen. Carbohydrates are the first molecules produced in photosynthesis, as lipids, proteins and nucleic acids are synthesised from them. There are three basic types of carbohydrate molecule; monosacharides, disaccharides and polysaccharides. Monosacharides are monomers or single sugars, the type varying on the number of carbon atoms in the chain. A disaccharide is a double sugar made from two monosacharides, and like monosacharides they are classed as sugars. Polysaccharides are multiple sugars, or polymers of many monosacharides.
Monosacharides are the chemical building blocks of other important carbohydrates. They are sweet-tasting, soluble in water and capable of reducing other chemicals by donating electrons to other substances. Glucose is a monosaccharide and is widespread within living things. It is the main source of energy for a large number of organisms and most of the common polysaccharides are glucose polymers. Glucose is a hexose and has 6 carbon atoms in its chain and has the formula C6H12O6. All other hexose sugars have the same formula, such a B-Glucose, Fructose and Galactose. They have the same formula, but have slightly different structure and so are known as Isomers of each other. The differences are very small but do greatly affect properties such as sweetness, digestibility and the nature of the polymers formed when the monomers join together.