Concept 4: Analyzing Cell
Communication
Chapter 11 in Campbell
Pg. 62-65 in Holtzclaw
Questions #22-27 p. 73; #7-8 p. 75
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, ligandgated 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
Signal Transduction Pathway
• Reception
• Transduction
• Response
Signal Transduction Pathway
• Reception: Receptors undergo changes in shape due to
an environmental stimulus
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)
Signal Transduction Pathway
•
Response: Two ways response is accomplished:
1.
Transcriptional Modification:
•
2.
↑ or ↓ mRNA production (turning genes on/off)
Post-Translational Modification:
•
Activates existing enzyme molecules
Signal Transduction
• Reception
• Transduction
• Response
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?