Chapter 11 Free Response Questions

Refer to the following sections of chapter 11 and answer the questions

1. The three stages of cell signaling are reception, transduction, and response (pages 190-191)
Explain what Earl Sutherland discovered while studying how the hormone epinephrine stimulates the breakdown of glycogen to glucose in the liver and muscles (he won the Nobel Prize for this important work). See the links in the lecture section with references to the details of his experiment- two different versions are available. Be sure to explain the specifics of his experiment. In particular make sure you explain what a signal-transduction pathway is and how it works. To help you visualize this process please view the CD ROM (it is online if you need it), activity 11.1.

2. Most signal receptors are plasma-membrane proteins (pages 192-194).
It turns out that there are three major types of membrane bound proteins that act as receptors. They all work in slightly different ways. Please describe and illustrate each type. You must illustrate this for each receptor to get full credit. Make sure you explain what is meant by a ligand.
To help you visualize this process please view the CD ROM (it is online if you need it), activity 11.2.
a. G-Protein Linked Receptors
b. Tyrosine-Kinase Receptors
c. Ion Channel Receptors

3. Explain the role of second messengers in cell signaling pathways. See CD ROM activity 11.3.
a. Explain how cAMP is used as a second messenger. Be sure to use illustrations and include the pathway.
b. Explain how calcium ion and inositol trisphosphate (IP3) are used as second messengers. Be sure to use illustrations and include the pathway.