Ch07 Lecture Notes-Cell Signaling and Communication

Ch07 Lecture Notes-Cell Signaling and Communication -...

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Lecture Notes by Ian Craine to accompany Life: The Science of Biology, Ninth Edition Sadava • Hillis • Heller • Berenbaum Chapter 7: Cell Signaling and Communication Introduction • Prairie voles ( Microtus ochrogaster ) display extensive after-mating bonding behaviors—the couple builds a nest, raises their pups together, and stays together for life. • In contrast, montane vole ( M. montanus ) displays none of these behaviors. • Neuroscientists have discovered peptides that act as brain intercellular signals creating these behaviors: when prairie voles mate all day long, their brains release a 9-amino-acid peptide (oxytocin in females; vasopressin in males). ( See in-text diagram of oxytocin molecule p. 129. ) • The peptide is circulated in the bloodstream, and binds—like key-and-lock—to specific cells with protein receptors. Prairie voles have abundant receptors in brain regions regulating postmating behaviors. • The peptide–receptor interaction starts a signal transduction pathway, which causes these notable changes in behavior among prairie voles. Montane voles have far fewer receptors, hence fewer postmating behaviors. • In experiments, a female prairie vole injected with oxytocin inhibitor before mating does not bond with the male, but if injected with oxytocin will bond with a male even without mating. • Vasopressin gives similar results in males. Also, montane vole males that were genetically manipulated to express vasopressin receptor amounts comparable to prairie voles behave like prairie vole males. • Among humans, neuroeconomist Paul Zaks found that investors that received oxytocin nasal spray were more trusting, and they invested more funds with strangers than investors that received inert spray. So the oxytocin signaling pathway is important in human behavior too. • Three sequential processes are involved in the cell’s response to a signal such as peptides. • The signal binds to a receptor protein. • The binding causes a message to be sent to the cell’s cytoplasm and to be amplified there. • The cell changes its activity in response to the signal. • ( See Video 7.1 ) 7.1 What Are Signals, and How Do Cells Respond to Them? • Both prokaryotic and eukaryotic cells must process information from their environment and calculate appropriate responses. • Signals may be chemical molecules or physical stimuli like light or heat.
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• Cells must be set up to interpret signals—not all cells can interpret all signals. • To interpret a signal, a cell must have the appropriate receptor protein. • In multicellular organisms, all cells have the genetic information for all receptor proteins, but due to differential gene expression, different cells have different receptors. Cells receive signals from the physical environment and from other
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This note was uploaded on 11/11/2011 for the course BIOL 101 taught by Professor Staff during the Spring '10 term at Howard.

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Ch07 Lecture Notes-Cell Signaling and Communication -...

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