Macromolecules Polymers are long molecules built by linking repeating units covalently. A single unit of a polymer is a monomer. The four main types of macromolecules are carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates There are three types of carbohydrates: monosaccharides, disaccharides, and polysaccharides. Monosaccharides consist of 1 monomer, disaccharides are made of 2 monosaccharides, and polysaccharides are composed of more than 2 monosaccharides. Carbohydrates are made of Carbon, Hydrogen, and Oxygen. The two functional groups are aldose (carbonyl group at the end of the molecules) and ketose (carbonyl group in the center of the molecule). Carbohydrates give immediate energy, store energy, and provide raw and structural materials. Polysaccharides can either be branched or linear. Branched polysaccharides have several end for glucose to be released quickly, while linear polysaccharides do not. Structural polysaccharides such as cellulose and chitin form cell walls. If the carbohydrate has an alpha configuration, it is folded in loops and is easier to digest. Beta configuration carbohydrates are formed in pleated sheets and are more difficult to digest. Lipids Lipids are composed of Carbon, Hydrogen, and Oxygen, but mostly hydrocarbons. Lipids include fats, waxes, steroids, pigments, and phospholipids. Lipids only form in their monomers, fatty acids. Lipids store energy, provide structure to cells, insulate the body, and fusion organs. Phospholipids have hydrophobic tails made of saturated and unsaturated fats and hydrophilic heads. They form the cell membranes by arranging in a bilayer with heads on the outside and tails on the inside. Saturated fats only have single bonds between carbon atoms and are solid at room temperature. The single bonds allow them to form straight lines and pack tightly together. Unsaturated fats have one or more double bonds between carbon atoms and which causes a bend in the structure so they can't pack as tightly together, causing them to be liquid at room temperature. Proteins Amino acids are the monomers of proteins and polypeptides are the polymers of proteins. Proteins consist of a sequence of the same 20 amino acids held together