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2.1 Molecules to metabolism

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Description

Nature of science:
Falsification of theories—the artificial synthesis of urea helped to falsify vitalism. (1.9)
Understandings:
  • Molecular biology explains living processes in terms of the chemical substances involved.
  • Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist.
  • Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids.
  • Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism.
  • Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions.
  • Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers.
Applications and skills:
  • Application: Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.
  • Skill: Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
  • Skill: Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.
Guidance:
  • Only the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose are expected in drawings.
  • Sugars include monosaccharides and disaccharides.
  • Only one saturated fat is expected and its specific name is not necessary.
  • The variable radical of amino acids can be shown as R. The structure of individual R-groups does not need to be memorized.
  • Students should be able to recognize from molecular diagrams that triglycerides, phospholipids and steroids are lipids. Drawings of steroids are not expected.
  • Proteins or parts of polypeptides should be recognized from molecular diagrams showing amino acids linked by peptide bonds.
 Utilization:
Syllabus and cross-curricular links:
Chemistry
Topic 4 Chemical bonding and structure
Option B Biochemistry

Aims:
  • Aim 7: ICT can be used for molecular visualization of carbohydrates, lipids and proteins in this sub-topic and in 2.3 and 2.4.
  • Aim 6: Food tests such as the use of iodine to identify starch or Benedict’s reagent to identify reducing sugars could be carried out.

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