SPEC

• Monomers are the smaller units from which larger molecules are made.
• Monomers are the smaller units from which larger molecules are made.
• Monosaccharides, amino acids and nucleotides are examples of monomers.
• A condensation reaction joins two molecules together with the formation of a chemical bond and involves the elimination of a molecule of water.
• A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule.
• Monosaccharides are the monomers from which larger carbohydrates are made.
• Glucose, galactose and fructose are common monosaccharides.
• A condensation reaction between two monosaccharides forms a glycosidic bond.
• Disaccharides are formed by the condensation of two monosaccharides.
• Maltose is a disaccharide formed by condensation of two glucose molecules.
• Sucrose is a disaccharide formed by condensation of a glucose molecule and a fructose molecule.
• Lactose is a disaccharide formed by condensation of a glucose molecule and a galactose molecule.
• Glucose has two isomers, α-glucose and β-glucose, with structures:

  
• Polysaccharides are formed by the condensation of many glucose units.
• Glycogen and starch are formed by the condensation of α-glucose.
• Cellulose is formed by the condensation of β-glucose.
• Triglycerides and phospholipids are two groups of lipid.
• Triglycerides are formed by the condensation of one molecule of glycerol and three molecules of fatty acid.
• A condensation reaction between glycerol and a fatty acid (RCOOH) forms an ester bond.
• The R-group of a fatty acid may be saturated or unsaturated.
• In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate-containing group.
• The different properties of triglycerides and phospholipids related to their different structures.
• Students should be able to:

  • recognise, from diagrams, saturated and unsaturated fatty acids
  • explain the different properties of triglycerides and phospholipids.
• The emulsion test for lipids:

  1. Add ethanol then add water.
  2. Shake.
  3. White emulsion = positive result.
• Amino acids are the monomers from which proteins are made. The general structure of an amino acid as:

  
• The twenty amino acids that are common in all organisms differ only in their side group.
• NH2 represents an amine group, COOH represents a carboxyl group and R represents a side chain.
• A condensation reaction between two amino acids forms a peptide bond.
• Dipeptides are formed by the condensation of two amino acids.
• Polypeptides are formed by the condensation of many amino acids.
• A functional protein may contain one or more polypeptides.
• The role of hydrogen bonds, ionic bonds and disulfide bridges in the structure of proteins.
• Proteins have a variety of functions within all living organisms. The relationship between primary, secondary, tertiary and quaternary structure, and protein function.
• The biuret test for proteins: Add 1cm3 of sample to 1cm3 of biuret solution. If present, the solution will turn from blue to purple.
• Students should be able to relate the structure of proteins to properties of proteins named throughout the specification.
• Each enzyme lowers the activation energy of the reaction it catalyses.
• The properties of an enzyme relate to the tertiary structure of its active site and its ability to combine with complementary substrate(s) to form an enzyme-substrate complex.
• The induced-fit model of enzyme action.
• The effects of the following factors on the rate of enzyme-controlled reactions – enzyme concentration, substrate concentration, concentration of competitive and of non-competitive inhibitors, pH and temperature.
• Students should be able to:

  • appreciate how models of enzyme action have changed over time
  • appreciate that enzymes catalyse a wide range of intracellular and extracellular reactions that determine structures and functions from cellular to whole-organism level.