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Cell Communication

Cell Communication - Cell Communication...

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Unformatted text preview: Cell Communication http://www.rkm.com.au/imagelibrary/thumbnails/IMMUNE-synapse-150.jpg 1 Last Time Active transport forms gradients maintenance by ion pumps electrochemical gradients membrane potential Neurons and membrane potential Neuron signals are generated by changes in membrane potential 2 Cell Communication Infrastructure of communication Extra-cellular structures Cell connections Communication signals - an overview Local and distance signaling 3 ECM - extracellular matrix Fig. 6.29 4 Cell wall Fig. 6.28 5 Cell to cell communication structures Animal cell junctions tight junction gap junction desmosomes Plant connections plasmodesmata 6 Cellular connections in animals 1. Tight junctions 2. Desmosomes 3. Gap junctions Fig. 6.31 7 Plasmodesmata 8 Communication Overview signal transduction pathway signaling molecules Model: single cell communication in yeast mating 9 Cell communication is fairly complex! A comprehensive map of the toll-like receptor signaling network (2006)Molecular Systems Biology 2:15 10 Yeast mating - communication between two single cells Hi there, big guy... a Each mating type secretes a chemical that binds to the other cell's receptor. 11 12 Local and distance signaling in multicellular organisms Local Communication by cells in direct contact Communication by cells not in direct contact Distance Communication between cells across a distance 13 Signaling by direct contact Junctions Cell-cell recognition 14 Other local signaling Paracrine Synaptic 15 Neuron communicationexample of local signaling neurons communicate with other cells (other neurons, muscle cells) at synapses Pre-synaptic cell releases chemical signal ("neurotransmitter") that is taken up by the post-synaptic cell, and elicits a response 16 Presynaptic cell Postsynaptic cell Synaptic vesicles containing neurotransmitter Na+ K+ Presynaptic membrane Voltage-gated Ca2+ channel Ca2+ Postsynaptic membrane Ligand-gated ion channels 17 Synaptic signaling summary Two neuron cells separated by a synapse Pre-synaptic neuron releases neurotransmitters into gap Post-synaptic neuron receptors bind neurotransmitter, opens Na+/K+ channel If more Na+ gets into post-synaptic cell depolarizes membrane, signal continues If more K+ gets into post-synaptic cell, hyperpolarization inhibits the signal 18 Long distance signaling Hormonal 19 Hormone signaling in animals blood glucose level rises insulin Stimulus EAT Homeostasis 90mg glucose/100ml blood blood glucose Stimulus glucagon level drops Fig. 45.12 20 Long distance signaling in plants recruitment of parasitic wasps, which lay eggs in caterpillar synthesis and release of airborne chemicals wounding chemical in saliva signal transduction pathway Fig. 39.29 21 Major themes Only specific target cells recognize and respond to given chemical signal Signal is received, transduced through the cells and elicits a response Cell communication and signaling is often in response to some trigger 22 Summary Infrastructure of communication Extra-cellular structures Cell connections Communication signals - an overview Local and distance signaling 23 Ungraded homework assignment Why is nerve cell signaling considered both long distance and local? How are glycoproteins involved in signaling? Compare and contrast plasmodesmata and gap junctions. 24 Next Time Signal transduction http://www.temple.edu/stl/images/SignalTransduction.jpg 25 ...
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