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Chapter 5 Blog:  Membrane Structure, Synthesis, and Transport (Erica)

Page history last edited by Derek Weber 13 years, 4 months ago

In the first section of this page, you will write a daily summary of that day's class.  For example in  your chapter 2 blog, your first entry should be titled 9/3/10.  You should then write a one or two paragraph summary of that day's lecture, outlining the major points.  In the second section, you are required to add two items (link to a website, video, animation, student-created slide show, student-created PowerPoint presentation) and one journal article pertaining to a topic in this chapter.  A one-paragraph summary must accompany each item describing the main idea and how it applies to the lecture topic.  Please see the PBWorks help guide for assistance embedding video and other items directly in the page.  I will also produce a how-to video on using tables to wrap text around items and other useful tips.  Please see the syllabus for organization and grading details.


A.  Daily Blog


September 29, 2010


     Today in class we learned about the one of the most common parts of a cell: the membrane.  Membranes are important because they control the chemical make-up of cells because of their selective import and export of ions of molecules, cell compartmentalization (separates organelles from the cytoplasm), protein sorting (like vesicles), gives the cell shape, aids in transport, produces enzymes, ATP, and other proteins, as well as cell signaling (the signal in the environment that binds to the membrane protein that then gives the signal to the cytoplasm which then makes the cell adapt). We then talked about leaflets which are associated with cytoskeleton and the matrix of a cell.  'we discussed how exocytosis helps build membranes because the synthesized proteins from the E.R. are sent through a vesicle to the membrane, in which the vesicle then diffuses (along with the protein) into the membrane.  Transmembrane proteins take things in and out of the cell, and the transmembrane domain is composed of amino acids and hydrophobics which can have a huge impact on how people have diseases due to transport and cell recognition.  The last thing we talked about were hydrophobics in a membrane protein and how it was produced.  Well, let me tell you, there are about 20-25 hydrophobics in a chain would be considered a transmembrane protein, and for the E.R signal sequence the N-terminus targets for cotranslational modification in the rough E.R.  


October 1, 2010


     We started off the lecture talking about transport, and how equilibrium is the worst fate for a cell.  Dr. Weber also mentioned that the membrane is selectively permeable due to the hydrophobic core and the hydrophilic outside.  We then discussed how diethylurea diffuses easier than urea because although it is a larger molecule, it is more nonpolar therefore more hydrophobic which makes it easier to diffuse through the membrane. The things that effect transport are: size, hydrophobicity (or the fear of water), charge, the concentration gradient (which may or made not need a channel protein) or the uneven distribution of a specific molecule.  The next thing we learned was the law of thermodynamics-energy is never created or destroyed, it is just transforme from one state to another, and disorder (entrepy) in the universe is always increasing. Molecules need to have disorder, or in cells they need a gradient, in order for things to happen in the cell otherwise it would be a "dead cell" because diffusion has to occur spontaneously.  Things that are unstable have a lot of potential energy because molecules always want their space, or to be spread out evenly.  Facilitated diffusion uses a transport protein also helps to release energy. A channel protein, when activated, is open on both sides.  A carrier protein which is involve din active transport and facilitated diffusion, is open on one side because of the hydrophilic pocket, and has a high specificity. The last thing we discussed for this chapter was the different types of transporters: the uniporter (transports single molecules/ions), symporter (two or more ions), antiporter (two or more ions transported in the opposite direction), carrier porteins that act as pumps to create concentration gradients, and the E2 conformation.  

B.  Useful Materials


  I wasn't sure what the exact definition of the fluid mosaic model was, but now I know that it's just the basic structure of the plasma membrane which I thought was described pretty well in this video although it is a pretty general description. 
Different types of transport!  This website describes the most common types of transport such as active transport which is the transporting of ions or molecules through the membrane against their concentration gradient, and facilitated diffusion which is what small hydrophilic molecules, like sugars, use to pass through cell membranes.  
Glutamate transporter GLAST-pubmed article In this article they discuss the glutamate transport (?) in a rat brain. This transport is mediated by the transporters GLT and GLAST which are ionic gradients generated by the ions NA+, K+, and ATPase inhibitors digoxin and ouabain.  Neither of these compounds caused ATPase activity, therefore they have not established a direct link between GLAST regulation and NA, K, and ATPase activity, although they have shown that ouabain and digoxin can interfere with GluT transport and should be considered potentially neurotoxic.  



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