Proteins, Carbohydrates and Lipids

• amino acids are the monomers for proteins
• dipeptides are formed by joining two amino acids in a condensation reaction
• polypeptides are formed by the condensation of many amino acids joined by peptide bonds
• amino acids contain NH2 which is the amine group and COOH represents a carboxyl group
• amino acids contains an R group, a carboxyl group, and an amine group
• the side chain or R group varies from one amino acid to another
• there are 20 different types of amino acids that can be combined together to form polypeptides
• fibrous proteins and globular proteins are known as functional proteins
• the sequence of amino acids will determine how the polypeptide chain folds which determines the shape of the protein
• monosaccharides are the monomers of carbohydrates
• common monosaccharides: glucose, galactose and fructose
• disaccharides are formed from 2 monosaccharides in a condensation reaction bonded by a glycosidic bond
• common disaccharides: maltose and sucrose
• polysaccharides are formed from many monosaccharides joined together by glycosidic bonds in a condensation reaction
• as polysaccharides are such large molecules they are usually insoluble in water, this makes them suitable to carry out storage and support functions
• common polysaccharides: glycogen, starch and cellulose
• lipids contain carbon, hydrogen and oxygen
• lipids are generally insoluble in water
• main groups of lipids: triglycerides and phospholipids
• main role of phospholipids: provides flexibility and transport mechanisms to the plasma membrane
• other roles of lipids: providing an energy store, insulation and protection
• triglyceride is made up of three fatty acids attached to one molecule of glycerol