Carbohydrates, lipids and proteins

Learning objectives

Explain how condensation reactions link monomers into polymers with the loss of water and how hydrolysis reverses the process, and identify the monomer of each of the main groups of macromolecules

Compare the structures of starch, glycogen and cellulose, and relate the differences between alpha and beta glucose linkages to the storage role of starch and glycogen and to the structural role of cellulose in plant cell walls

Describe triglycerides as a glycerol molecule joined to three fatty acids by ester bonds, distinguish saturated, monounsaturated and polyunsaturated fatty acids and cis from trans isomers, and compare lipids and carbohydrates as energy stores in terms of energy per gram, solubility and speed of mobilisation

Describe the structure of phospholipids and (HL) steroids, and explain how the amphipathic nature of a phospholipid suits it to forming a bilayer

Describe an amino acid as a central carbon bearing an amine group, a carboxyl group and a variable R group, explain how condensation forms peptide bonds, and explain why twenty amino acids allow an immense diversity of polypeptides

Explain denaturation by heat and by extremes of pH, and (HL) distinguish the primary, secondary, tertiary and quaternary levels of protein structure, name the interactions that stabilise each level, and contrast fibrous with globular proteins using named examples