AS/A Biology | Biomolecules | Lesson plan


Jul22 - Aug15 (3 weeks)


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

Learning Outcomes

Students should be able to:

  • understand that biological macromolecules like cellulose, proteins and DNA are polymers made of monomers with distinct chemical properties
  • describe the ring forms of α-glucose and β-glucose
  • describe the formation and breakage of a glycosidic bond with reference both to polysaccharides and to disaccharides including sucrose
  • describe the molecular structure of polysaccharides including starch (amylose and amylopectin), glycogen and cellulose and relate these structures to their functions in living organisms
  • describe the molecular structure of a triglyceride and a phospholipid and relate these structures to their functions in living organisms
  • describe the structure of an amino acid and the formation and breakage of a peptide bond
  • 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
  • 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)
  • describe and explain the roles of water in living organisms and as an environment for organisms
  • use the knowledge gained in this section in new situations or to solve related problems.

Teaching Process

  • Most of the concepts are theoretical.
  • Importance of the structure to the function is emphasized.
  • Each property of the molecules is taught with reference to its necessity and consequences to life.
  • The tests for biomolecules would be conducted once the students understand the mechanisms behind the tests involved.


  • test for reducing and non-reducing sugars (including using colour standards as a semi-quantitative use of the Benedict’s test)
  • test for starch using iodine in potassium iodide solution
  • test for lipids using the emulsion test
  • test for proteins using biuret reagent
  • The protein folding game: foldit []

References and suggested reading


  • Whatif exercise (based on Students are asked weird hypothetical questions, to which they must research or figure out a genuine answer.
  • Written test to evaluate their understanding of the important concepts.
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