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Gap Junctions & Plasmodesmata. BY: KRISTIN HUNTER. What is a gap junction?. An intercelluar junction in animal cells that provide a cytoplasmic channel from one cell to an adjacent cell Not found in skeletal muscle fibers and free circulating cells. Composition of the Gap Junction.
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Gap Junctions & Plasmodesmata BY: KRISTIN HUNTER
What is a gap junction? • An intercelluar junction in animal cells that provide a cytoplasmic channel from one cell to an adjacent cell • Not found in skeletal muscle fibers and free circulating cells
Composition of the Gap Junction • Composed of two connexons (hemichannels) which connect across intercellular space - Each connexon is composed of six copies of connexins (transmembrane proteins)
Function of Gap Junction • Provides cytoplasmic channels between adjacent cells • Allow passage way for: - Sugars - Amino acids - Ions - Small molecules • Necessary for communication between cells in tissues
Function of Gap Junction Cont. • Able to isolate and kill defective cells • Electrical coupling - Action potential due to depolarization (cell has positive charge) - Signals set off from action potential culminate in a muscle contraction • Aids in metabolic coupling - Cyclic AMP passes through and transmits message of hormones
What is a plasmodesma? • An open channel in the cell wall of a plant that connects the cytoplasm of an adjacent cell
Function of Plasmodesmata • Connects the chemical environment of adjacent cells - Plasma membranes of adjacent cells line channel of each plasmodesma unifying plant into one living continuum • Allows passage way for: - Cytosol - Water - Small solutes - Certain proteins and RNA molecules (under some circumstances)
Function of Plasmodesmata Cont. • Regulate trafficking of large molecules through relaxation or restriction of size exclusion limit ( maximum size of molecule that can be transported)
Works Cited • Campbell, and Reece. AP Edition Biology. 8th ed. Pearson. Print. • "Gap junction." Wikipedia, the free encyclopedia. Web. 27 Sept. 2009. <http:// en.wikipedia.org/wiki/Gap_junction>. • "Index of /~cmallery/150/cells." University of Miami Department of Biology. Web. 27 Sept. 2009. <http://www.bio.miami.edu/~cmallery/150/cells/>. • "Junctions Between Cells." RCN New York City | Digital Cable TV, High-Speed Internet Service & Phone in New York City, including Queens, Brooklyn and Manhattan. Web. 27 Sept. 2009. <http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/J/ Junctions.html#gap>. • "Nexus - Gap-junction Dr.Jastrows EM-Atlas." Johannes Gutenberg-Universität Mainz - Homepage - Johannes Gutenberg-Universität Mainz. Web. 27 Sept. 2009. <http:// www.uni-mainz.de/FB/Medizin/Anatomie/workshop/EM/EMNexus.html>. • Photograph. Wikipedia, the free encyclopedia. Web. 27 Sept. 2009. <http:// upload.wikimedia.org/wikipedia/th/d/d3/Plasmodesmata_structure.jpg>. • "Plasmodesmata (Gateways for virus invasion)." The John Innes Centre. Web. 27 Sept. 2009. <http://www.jic.ac.uk/staff/andy-maule/plasmodesmata.htm>. • Web. 27 Sept. 2009. <http://webmedia.unmc.edu/>. • Web. 27 Sept. 2009. <http://www.bbioo.com/bio101/2006/6158.htm>. • Web. 27 Sept. 2009. <http://www.cn-yq.com/cp11.htm>. • "What Are Gap Junctions?" WiseGEEK: clear answers for common questions. Web. 27 Sept. 2009. <http://www.wisegeek.com/what-are-gap-junctions.htm>.