1. Concept 4: Analyzing Cell Communication
Chapter 11 in Campbell
Pg in Holtzclaw Questions #22-27 p. 73; #7-8 p. 75

2. Cell Communication You must know:
The three stages of cell communication: reception, transduction, and response (the signal transduction pathway!)
Applications/Examples!
How G protein-coupled receptors, receptor tyrosine kinases, ligand-gated ion channels, and intracellular receptors receive cell signals and start transduction
How a cell signal is amplified by a phosphorylation cascade, via second messengers (such as cAMP or Ca2+ ions) and protein kinases.
How a cell response in the nucleus turns on genes, whereas in the cytoplasm it activates enzymes
What apoptosis means and why it is important to normal functioning of multicellular organisms

3. Signal Transduction Pathway
Reception
Transduction
Response

4. Signal Transduction Pathway
Reception: Receptors undergo changes in shape due to an environmental stimulus

5. Signal Transduction Pathway
Transduction: Amplification of signal through a multistep pathway
Allows small signal to produce large cellular response
Uses protein kinases (phosphorylation cascade) and second messengers (Ca2+ and cAMP)

6. Signal Transduction Pathway
Response: Two ways response is accomplished:
Transcriptional Modification:
↑ or ↓ mRNA production (turning genes on/off)
Post-Translational Modification:
Activates existing enzyme molecules

7. Signal Transduction
Reception
Transduction
Response
Act Out!

8. Sample Questions
Describe the signal transduction pathway in terms of reception, transduction, and response.
Explain the two ways that responses can be accomplished
A hormone molecule ends up blocking RNA polymerase from attaching to a specific gene. Is this response transcriptional modification or post-translational?