activated rhodopsin triggers a signal transduction cascade
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Activated rhodopsin triggers a signal transduction cascade. Reminder on Ion Distribution and Transport in Cells. Cells (eukaryotes) divided into a number of membrane-bound compartments. Concentrations in different compartments can be orders of magnitude different. - PowerPoint PPT PresentationTRANSCRIPT
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Activated rhodopsin triggers a signal transduction cascade
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Reminder on Ion Distribution and Transport in Cells
Cells (eukaryotes) divided into a number of membrane-bound compartments.Concentrations in different compartments can be orders of magnitude different.Proteins (ion channels, transporters) mediate these concentration gradients.Membrane proteins central to huge range of processes – cell signaling, nerve impulses, nutrient transport, etc.
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Ion Channels and Transient Permeability
Channels open in response to a variety of different stimuli.Key mechanisms are voltage gating, ligand binding-induced gating and mechanical tension in the membrane.
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Mwc models of ligand-gated channels
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Light-induced hyperpolarization of the rod cell membrane
Hydrolysis of cGMP causes cation channels to close
Rod cell membrane hyperpolarizes
cGMP
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Electrical consequences of illumination
http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Retina/ReceptorPotential.html
Each dot in the figure below represents delivery of a very dim pulse of light containing only a few quanta. Voltage responses appear to come in 3 sizes: none, small, and large, representing the detection of 0, 1 or 2 quanta in each flash. The granularity of response to dim light stimuli is evident.
http://webvision.med.utah.edu/book/part-ii-anatomy-and-physiology-of-the-retina/photoreceptors/
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Synapse diffusion
http://www.colorado.edu/intphys/Class/IPHY3430-200/008sensory.htm
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication
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Other examples of synaptic communication