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1991 The Center for Applied Research in Education

THE CELL MEMBRANE

Background:

If a cell is viewed in cross section, it resembles the diagram at right. Its membrane faces water on the exterior and on the interior. Molecules called phospholipidls make up the basic structure of the cell membrane.

How do these molecules arrange themselves so that the cell mem- brane is held together? It turns out that phospholipid molecules contain two regions (pictured in the diagram below): the ‘head,’ which tends to orient towards water, and the “tail,” which tends to move away from water.
 

Your Task :

Follow the directions below to demonstrate how the phospholipid molecules arrange themselves so that all ‘water-loving’ regions contact water, and all “wa- ter-hating’ regions face away from water.

1. On the sheet labeled CELL MEMBRANE IN CROSS SECTION, label all regions which contain water.
2. Cut out about ten phospholipid molecules from the sheet provided by cutting along the straight lines.
3. Arrange the phospholipid molecules within the cell membrane cross section, making sure the “head” regions contact water and the “tail” regions face away from water.
4. Have your teacher approve your arrangement, then continue it by cutting out and gluing more phospholipid molecules around the cell membrane region.

cell membrane

Cell Membrane in Cross Section

phosopholipids

Phospholipids

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

These pages authored and maintained by Marcella Dawson. Revised 3/2002 . Copyright 1995 CRPC GirlTECH. All rights reserved. . Email your comments. These pages were developed through GirlTECH '96, a teacher training and student technology council program sponsored by the Center for Research on Parallel Computation (CRPC), a National Science Foundation Science and Technology Center.