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

Page history last edited by Emad Madha 13 years, 2 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


In today's class, our lecture focused primarily on the biological membranes of the cell. We discussed the framework of the membrane, which is made of a phospholipid bilayer. The hydrophobic region of the phospholipids faces in, while the hydrophilic region faces out. These membranes are also riddled with proteins. The membrane, as we learned, is a mosaic of lipids, proteins, and carbohydrate. The proteins of the membrane are bound to the membrane. The main types of membrane proteins are either integral of peripheral. Integral proteins are further divided into transmembrane proteins and lipid-anchored proteins. Transmembrane proteins are physically embedded in the hydrophobic region, while lipid-anchored proteins are attached covalently to a lipid. Peripheral proteins are noncovalently attached to parts of integral proteins that project out of the membrane, or are bound to the polar head groups of phospholipids. We learned that about 25% of all genes encode membrane proteins. This means that these proteins are very important to a cells survival. We also learned that membranes are semifluid. This means that most of the lipids can rotate freely around their long axes and move laterally within the membrane leaflet. What affects the fluidity of the membrane is the length of fatty acyl tails, the presence of double bonds in acyl tails, and the presence of cholesterol. The shorter the acyl tail, the less likely it is to interact, thereby making the membrane more fluid. The presence of double bonds in acyl tails cause kinks that inhibit neighboring tails from interacting with it, making the membrane more fluid. Cholesterol affects a membrane's fluidity by stabilizing the membrane.



Today's lecture took on the general Friday lecture format. In class, we discussed the process of membrane transport. We discussed gradients and how equilibrium kills a cell. We discussed how concentration gradients give cells energy essential for living, making the Laws of Thermodynamics relevant to cells. We learned about the way molecules and ions are transported, through passive and facilitated diffusion. We discussed the different types of transporters, which are uniporters, cotransporters, and antiporters. Uniporters bind single ions or molecules and transport them across a membrane. Cotransporters bind two or more ions or molecules and transport them in the same direction across the membrane. Antiporters bind two or more ions or molecules and transport them in opposite directions across membranes.


B.  Useful Materials

This video comes from a source I found on YouTube for a previous blog. In this video, the processes of passive transport are discussed. The video explains the processes of simple diffusion, facilitated diffusion, and osmosis. Relating back to what we learned in class, the video describes one of the major processes that bring materials into a cell, describing how the phospholipid bilayer is used as a tool in these processes.


This is a short video that summarizes the fluid mosaic model. It helps to visualize what we learned in class, about hydrophobic and hydrophilic regions of the plasma membrane, the semi-fluidity of the membrane, and a little bit about the function of transmembrane proteins. This relates back to our lecture that went over the structure of the cell membrane.



This PubMed journal describes the relation between the mutations in transmembrane transporter protein and mental-retardation syndromes. It specifies the monocarboxylate transporter 8 protein, which transports thyroid hormone in the brain, and how mutations in it can lead to Allan-Herndon-Dudley Syndrome. The abstract describes how aspects of nerve cells are dependent on thyroid hormone, which means that with out the hormone, they will not function properly. This means that a mutated transporter protein could be directly responsible for some mental-retardation syndromes.


Comments (1)

Derek Weber said

at 3:30 am on Nov 23, 2010


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