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Cellular Membrane and Signaling: Structure, Transport, and Communication

This article discusses the fluid mosaic model of the membrane, passive and active transport, osmosis, endocytosis and exocytosis, and cellular signaling pathways. It provides a comprehensive understanding of membrane function and cell communication.

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Cellular Membrane and Signaling: Structure, Transport, and Communication

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  1. What do you remember?

  2. “Fluid Mosaic Model” Membrane held in place by mostly hydrophobic interaction Most lipids and some proteins drift randomly

  3. Factors influencing fluidity 1) Phospholipid structure

  4. 2)

  5. flowchart

  6. Transport Passive transport Diffusion Down concentration gradient Simple vs. Facilitated Simple diffusion molecules diffuse through the lipid portion What types of molecules can do this?

  7. Facilitated Diffusion Requires help (Protein) Why would it need help? Examples: carrier/transport proteins ion channels gated ion channels aquaporins

  8. Osmosis Diffusion of water -through a selectively permeable membrane Uses aquaporins Comparative terms Hypertonic Hypotonic Isotonic ALWAYS refer to SOLUTE concentration

  9. What will happen to fluid levels? Which direction will water move? A B B A Selectively permeable membrane Which side has a higher solute concentration? Which side has a higher water concentration? Which side is hypertonic? Which side is hypotonic?

  10. Active Transport Movement of a solute against its concentration gradient -many times use ATP as energy ex: Na+/K+ pump http://highered.mheducation.com/sites/9834092339/student_view0/chapter38/how_the_sodium_potassium_pump_works.html Proton pump is major electrogenic pump in plants, fungi, and bacteria

  11. Cotransport Use the concentration gradient produced by one pump to move a second molecule against its concentration gradient high sucrose low sucrose Ex: Plants use this to load sugar (from photosynthesis) into specialized cells (phloem) so it can be transported throughout the plant http://highered.mheducation.com/sites/9834092339/student_view0/chapter38/cotransport__symport_and_antiport_.html

  12. https://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio02.swf::Endocytosis%20and%20Exocytosishttps://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120068/bio02.swf::Endocytosis%20and%20Exocytosis

  13. Apply to a functioning neuron http://highered.mheducation.com/sites/0072495855/student_view0/chapter14/animation__the_nerve_impulse.html

  14. Resting potential charge difference on either side of membrane

  15. Na+ is main cation Negatively charged proteins are main anions K+ is main cation

  16. Na+ channels behind (toward the cell body) cannot be reactivated for a period of time Ensures that action potentials are one way

  17. Saltatory conduction

  18. https://www.youtube.com/watch?v=y6PUs4Xy_nw

  19. Local signaling Electrical signal triggers release of neurotransmitter. Synaptic signaling Neurotransmitter diffuses across synapse. Target cell

  20. https://youtu.be/JjHMGSI_h0Q http://www.hhmi.org/biointeractive/prialt-blocks-motor-synapse-fish http://www.hhmi.org/biointeractive/prialt-blocks-pain-signaling-mice

  21. Local signaling Target cells Paracrine signaling -ex: growth factors used to stimulate target cells to grow and divide Secreting cell Secretory vesicles Local regulator -ex: growth factor

  22. Long-distance signaling  endocrine signaling …hormones!!! Target cell specifically binds hormone. Endocrine cell Hormone travels in bloodstream. Blood vessel

  23. Cell signaling occurs in 3 stages EXTRA- CELLULAR FLUID CYTOPLASM Plasma membrane Reception Receptor Signaling Molecule -ligand

  24. EXTRA- CELLULAR FLUID CYTOPLASM Plasma membrane Transduction Reception Receptor 1 2 3 Relay molecules Signaling molecule

  25. EXTRA- CELLULAR FLUID CYTOPLASM Plasma membrane Transduction Reception Response Receptor 1 2 3 Activation Relay molecules Signaling molecule

  26. Reception Gate closed Ions Signaling molecule (ligand) Plasma membrane Ligand-gated ion channel receptor

  27. Gate open Gate closed Ions Signaling molecule (ligand) Cellular response Plasma membrane Ligand-gated ion channel receptor

  28. Gate open Gate closed Ions Signaling molecule (ligand) Cellular response Plasma membrane Ligand-gated ion channel receptor Gate closed

  29. Inactive enzyme Signaling molecule Activated GPCR Figure 5.21-s1 GTP Plasma membrane Activated G protein CYTOPLASM G protein-coupled receptor -large class of receptors that have a variety of responses -similar in structure … evolved early in life’s history

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