#7.1 Biological molecules - Syllabus 2015

• Structure of carbohydrates, lipids and proteins and their roles in living organisms
• Water and living organisms


Learning Outcomes

Candidates should be able to:

(a) [PA] carry out tests for reducing and non-reducing sugars (including using colour standards as a semi-quantitative use of the Benedict’s test), the iodine in potassium iodide solution test for starch, the emulsion test for lipids and the biuret test for proteins;

(b) describe the ring forms of α-glucose and β-glucose (candidates should be familiar with the terms monomer, polymer and macromolecule);

(c) describe the formation and breakage of a glycosidic bond with reference both to polysaccharides and to disaccharides including sucrose;

(d) describe the molecular structure of polysaccharides including starch (amylose and amylopectin), glycogen and cellulose and relate these structures to their functions in living organisms;

(e) describe the molecular structure of a triglyceride and a phospholipid and relate these structures to their functions in living organisms;

(f) describe the structure of an amino acid and the formation and breakage of a peptide bond;

(g) explain the meaning of the terms primary structure, secondary structure, tertiary structure and
quaternary structure of proteins and describe the types of bonding (hydrogen, ionic, disulfide and
hydrophobic interactions) that hold the molecule in shape;

(h) describe the molecular structure of haemoglobin as an example of a globular protein, and of collagen as an example of a fibrous protein and relate these structures to their functions (the importance of iron in the haemoglobin molecule should be emphasised. A haemoglobin molecule is composed of 2 alpha (α) chains and 2 beta (β) chains, although when describing the chains the terms α-globin and β-globin may be used. There should be a distinction between collagen molecules and collagen fibres);

(i) describe and explain the roles of water in living organisms and as an environment for organisms;

(j) use the knowledge gained in this section in new situations or to solve related problems.