Tuesday, September 14, 2010

8.6 Self Assembly In Cells

How can amphiphilic molecules account for their hydrophobic tale in a water environment? Figure 8.5 solves this self-assembly by using a sphere. To form a sphere the hydrophilic head must be wider than its tail. Not all amphiphiles can take this arrangement, for example two tailed molecules can form a bilayer membrane.

These two tailed amphiphiles are usually of the class phospholipids. These are the major component of cell membranes. The reasons for this are:
  • Self-assembly of phospholipids is more frequent than one chain surfactants because the hydrophobic cost of two chains exposed to water is twice as great as a single chain
  • Phospholipids spontaneously form closed surfaces (vesicles) to avoid exposing hydrocarbon chains
  • They are easy to synthesis in cells
  • The permeability of phospholipids membranes have favourable values
  • The fluid mosaic allows ease of changing shape
  • The fluid mosaic can accept embedded objects
All these factors make a working cell possible.

1 comment:

  1. What I like about self assembly of lipid aggregates in cells is when you have a lipid which has a hydrophobic head and a hydrophilic tail, as this creates a reverse micelle. The fluid mosaic is a really interesting topic to look at also, as we always hear about how the bilayer is semipermeable, allows the motion of transporters through it, as well as small ions etc.