11. Applications of chemistry - 11.1 The chemistry of life

At the end of this course candidates should be aware of the diverse variety of roles played by proteins. These will be illustrated by examples in this section and in sections 11.2 and 11.3. The recall of specific examples will not be tested but candidates will be expected to discuss the chemistry of given examples.


I Protein chemistry

II Genetic information

III Energy

IV Metals in biological systems

Learning outcomes

Candidates should be able to:

(a) recall that proteins are condensation polymers formed from amino acid monomers and recognise and describe the generalised structure of amino acids (link to core syllabus, sections 10.7 and 10.8)

(b) explain the importance of amino acid sequence (primary structure) in determining the properties of proteins

(c) distinguish between the primary, secondary and tertiary structure of proteins and explain the stabilisation of secondary and tertiary structure using the chemistry learnt in the core syllabus, sections 3 and 10.7

(d) describe and explain the characteristics of enzyme catalysis, including

(e) given information, use core chemistry to explain how small molecules interact with proteins and how they can modify the structure and function of biological systems (for example, as enzyme inhibitors or cofactors, disrupting protein-protein interactions, blocking ion channels) (link to 11.3 (a))

(f) describe the double helical structure of DNA in terms of a sugar-phosphate backbone and attached bases (Candidates will be expected to know the general structure in terms of a block diagram but will not be expected to recall the detailed structures of the components involved. Where these are required they will be given in the question paper.)

(g) explain the significance of hydrogen-bonding in the pairing of bases in DNA in relation to the replication of genetic information

(h) explain in outline how DNA encodes for the amino acid sequence of proteins with reference to mRNA, tRNA and the ribosome in translation and transcription

(i) explain the chemistry of DNA mutation from provided data

(j) discuss the genetic basis of disease (for example, sickle cell anaemia) in terms of altered protein structure and function

(k) explain how modification to protein/enzyme primary structure can result in new structure and/or function

(l) outline, in terms of the hydrolysis of ATP to ADP + Pi , the provision of energy for the cell

(m) understand why some metals are essential to life and, given information and with reference to the chemistry of the core syllabus, be able to explain the chemistry involved (for example, iron in haemoglobin (section 9.5 (g) and 11.1(e) and (j)), sodium and potassium in transmission of nerve impulses (section 3, ion solvation and section 5, energetics), zinc as an enzyme cofactor (section 10.1, nucleophilic attack, 11.1(e)))

(n) recognise that some metals are toxic and discuss, in chemical terms, the problems associated with heavy metals in the environment entering the food chain, for example mercury (development of methods to detect and address these problems will be discussed in 11.2(i) and 11.3(f))