CellCommunicationLarger.pdf - Cell-to-Cell Communication...

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Cell-to-Cell Communication The combined effects of multiple signals determine cell response Essential for multicellular organisms Important for unicellular organisms too 1
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Cell signaling Signal transduction pathway signal from outside the cell series of steps specific cellular response 2
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Pathway similarities Ancestral signaling molecules evolved in prokaryotes Modified in eukaryotes Cell signaling 3
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Fig. 11-3 Individual rod- shaped cells Spore-forming structure (fruiting body) Aggregation in process Fruiting bodies 0.5 mm 1 3 2 Signals in bacteria: •Quorum sensing (regulation of gene expression) •Ex. Biofilm formation Source: Campbell et al., 2008 4
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This species’ ability to "talk" has led to increased incidence of food poisoning in the developed world. Signal: acyl-homoserine lactone Assess group density and signal aggregation Image source: Cell signaling in Salmonella enteritidis 5
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Respond to stimulus Secrete ligands (signaling molecules) Ex. hormones and neurotransmitters Sensory cells 6
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Local and long distance signaling Synaptic signals Direct contact Source: Solomon, Berg, and Martin, 2011, Biology 9 th edition, Brooks/Cole, Cengage Learning, Belmont, CA. 7
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Local and long distance signaling Endocrine Neuroendocrine Autocrine Paracrine Ex. Growth factors Clotting factor Source: Solomon, Berg, and Martin, 2011, Biology 9 th edition, Brooks/Cole, Cengage Learning, Belmont, CA. 8
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Local regulators : messenger molecules that travel only short distances Hormones: chemicals used in long-distance signaling Plant growth regulators = hormones Ex. Ethylene (C 2 H 4 ), important in fruit ripening Synthesis: enzymatic reaction, needs O 2 , inhibited by CO 2 How do we manipulate this system to our advantage? Local and long distance signaling 9
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Hormones: chemicals used in long-distance signaling Plant growth regulators = hormones , different than animal hormones Ex. Green leaf volatiles Seem to distinguish among herbivore species How do the plants know? Attract predators of the herbivores Signal nearby plants Local and long distance signaling 10
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The Three Stages of Cell Signaling: A Preview Earl W. Sutherland discovered how the hormone epinephrine acts on cells Sutherland suggested that cells receiving signals went through three processes: Reception Transduction Response 11
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Three Stages of Signal Transduction Reception , transduction , and response are common to all signaling systems – although they vary greatly in detail Outside cell Signal Receptor Cytoplasmic end of receptor Activation Molecules that transfer signal down the pathway Molecule that brings about response Change in cell Cytoplasm 2 1 3 Figure 9-3 Reception Transduction Response 12
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Reception: A signal molecule binds to a receptor protein, causing it to change shape Specific binding between a signal molecule ( ligand ) and receptor A shape change in a receptor Most receptors are plasma membrane proteins 13
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