FOOD MACROMOLECULES INTRODUCTION Biological Macromolecules
Most common elements in living things are carbon, hydrogen, nitrogen, and oxygen. These four elements constitute about 95% of your body weight. All compounds can be classified in two broad categories ---organic and inorganic compounds. Organic compounds are all based on carbon. Carbon can form single bonds with another atom and also bond to other carbon molecules forming double and triple bonds. This allows carbon based molecules to form single and double rings, chains, and branching chains. Most organic compounds are built primarily of carbon, hydrogen, and oxygen but in different ratios. Each small organic molecule can be a unit of a large organic molecule called a macromolecule. If the small organic units are identical or form patterns they are called monomers and the large organic molecule they form is called a polymer.
When monomers are joined together the reaction is called dehydration synthesis or condensation as water is produced when the monomers are bonded together. To break the polymers down again the reaction is called hydrolysis. Notice how water is used or produced in these two reactions shown to the right.
There are four classes of macromolecules: carbohydrates, lipids, proteins, and nucleic acids. Heterotrophs, like us, must get these biological macromolecules from our food which we break down into monomers through digestion. This makes the molecules small enough to cross cell membranes. Our cells use them either as energy sources or to build the carbohydrates, proteins, lipids, and nucleic acids that our body needs

Questions:
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What atom makes up the backbone of biological macromolecules?