Cell Signalling

Discuss the ways in which signalling molecules can be classified, and an over-view of the classification of cell membrane receptors.  Also explain in your introduction how hydrophobic signalling molecules may produce a cellular response.  (Approximately 850 words)
You should then describe in detail the signal transduction pathways for a) a G-protein coupled receptor using either glucagon or ADH as an exemplar, and b) a receptor tyrosine kinase pathway using either insulin or epidermal growth factor (EGF) as an exemplar.  For each of your chosen signal pathways analyse its importance to the correct functioning of the organism and indicate problems that might result from errors in signalling.  You may integrate images into your essay to support your discussion and analysis.