Reading Guide: Pratt & Cornely, Chapter 10.1-10.2
1. Define signal transduction. Every signal transduction pathway requires both a
receptor and a _________ to get started.
2. What is the mathematical expression of a dissociation constant? What is the
dissociation constant equivalent to in enzyme kinetics? What is the shape of the
curve that expresses the % bound receptor as a function of ligand concnentration?
3. What is quorum sensing, and why do single cells have to communicate with one
another?
4. What is the difference between an agonist and an antagonist? How does caffeine
keep you awake?
5. What are the two common types of receptors? Which acts through second
messengers? Which acts through phosphorylation? Draw a simple schematic of both
signal transduction pathways from ligand binding through cellular effect.
6. What is the law of homeostasis? How is this related to desensitization?
7. What is the basic structure of a G-protein coupled receptor? How does a ligand
binding efent start the signal transduction?
8. What is the basic structure of a G-protein? Is it membrane-associated? How does
the G-protein become activated? How does it become deactivated?
9. What is the target of the free -subunit of a G-protein? What reaction does it
catalyze? Draw the structure of this second messenger.
10. What is the target of cAMP? What reaction does this enzyme catalyze?
11. Why is protein kinase A activated by phosphorylation?
12. Give an overview of the pathway in which epinephrine (adrenaline) signal leads to
release of glucose as an energy source for fight-or-flight.
13. How are each of these components of the G-protein mediated signal transduction
pathway shut off: G-protein, , cAMP, protein kinase A?
14. Draw a simple diagram for both the  and -adrenergic receptor medicated signal
pathways. Indicate points at which each pathway can be turned off.
15. How can the same hormone cause different responses in different tissues? How can
different hormones cause the same response within a cell?