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Membranes

Membranes

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Description:

By the end of this lesson, you will be able to: 

  • describe in detail the structure of the cell membrane.  This description must include: 
    • a description of the structure and function of the lipids and proteins that make up the membrane,
    • an explanation as to why the molecules of the membrane are organized the way they are,
    • how small pores can exist in the phospholipid bilayer,
    • glycoproteins and glycolipids,
    • attachment of cytoskelton,
    • location and role of cholesterol molecules
  • draw and label a diagram to illustrate the Fluid Mosaic model of the cell membrane.
  • explain how the Fluid Mosaic model of the plasma membrane accounts for the experimental data relating to the structure of the membrane and how this model has been modified to accommodate new experimental data.

All cell membranes have a universal structure of a phospholipid bilayer with globular proteins interspersed throughout, much like a mosiac.  Proteins can stick partly through the membrane (periperal) or go all the way through the membrane from one side to the other (transmembrane, peripheral).  This tutorial goes through the history of the development of the Fluid Mosaic model to show how new information is incorporated into viable scientific explanations.  

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Tutorial

The biophysical properties of phospholipids and proteins can be seen in the way they form membranes. The video begins with a highlight of the historical development of the Fluid Mosaic model of the Cell Membrane. Emphasis is placed on the biophysical properties of these molecules. Any good scientific explanation continues to be modified as new information is learned. The video finishes with some relevant research published in June 2014.

Source: M. O'Mahony, open source figures

The Inner Life of the Cell

BioVisions, (Harvard University) has produced this animation "The Inner Life of the Cell".

Watch this - and find the references to the cell membrane structure and function within it.

http://multimedia.mcb.harvard.edu/anim_innerlife.html

Source: BioVisions, Harvard University

Phospholipid Bilayer - Fatty Acid Vesicle Formation

Fatty Acid Vesicle Formation

De novo vesicle formation from fatty acid micelles - Protons are represented by the small glowing spheres. Upon protonation, the micelle structure becomes more fluid and may allow for larger numbers of micelles to join together. Vesicle formation occurs by chance after the fatty acid sheet has reached a threshold surface area.

 

http://molbio.mgh.harvard.edu/szostakweb/exploringOriginsDownloads/denovoVesicle.mov

 

Source: Janet Iwasa, Harvard Animation Collections

Membranes

This is the notes template for the lesson.

Full Screen

Source: M. O'Mahony, open source images