Notes for Chapter 13, pages 437-444

How many of the signals listed in Table 13-1 are familiar to you.

Terms you should be able to define and describe with examples:

• specificity
• amplification by enzyme cascades
• desensitization
• integration

Scatchard analysis is a wonderful tool.  However, only the folks taking the biochemistry lab will get to work with it.  This type of analysis is used to determine K_d and the number of ligand binding sites.  Everyone needs to know what K_d  is.

What are the general features of all signal transduction systems?  Figure 13-2 has examples of each of the four basic types of signalling mechanisms.

The discussion of gated ion channels is very similar to what you read in chapter 12.   The transmembrane potential is Vm (aka Dy).   The symbol E is given to the membrane potential at equilibrium.  So, to get from  equation13-1 to equation 13-2, substitute E for Vm, substitute "n" for "z", set DG to zero, subtract nFE from both sides, and divide both sides by nF.  Viola!  You have the Nernst equation.   Use it to work problem #6.

It was interesting to note that the number of sodium, potassium and chloride ions that come rushing in to change a membrane potential are miniscule when compared to the total ion concentration.  Calcium ion concentrations are kept very low inside the cytosol, so the Ca⁺² levels are significantly altered.

The discussion of acetylcholine receptor should also look familiar.  You should now be able to fully describe the acetylcholine receptor.  How does acetylcholine bind?  What happens when it does?  What does acetylcholinesterase do?  What happens if the acetylcholinesterase isn't functioning properly?