GROUP: ______________ DATE: _____________
Background:
If a cell membrane is viewed in cross section, it looks like the picture on the back of this paper. Both the cell’s exterior and interior membrane face water. The shape of the cell membrane is of two layers of phospholipids sandwiched together.
How do these molecules make the cell membrane? How do these molecules arrange themselves so that the cell membrane is held together?
It turns out that the phospholipid molecules contain two regions (see diagram below).
The glyce rol “head” of the phospholipid molecule is polar and attracts toward water.
This attraction is considered water-loving or HYDROPHILIC. In contrast, the fatty acid
“tail” of the phospholipid molecule is non-polar and moves away from water. This is considered water-fearing or HYDROPHOBIC. Figure below is a phospholipid molecule.
“head” (polar region)
“tail” (non-polar region)
Directions : Follow the directions below to draw a general cell membrane cross section.
Use the cell cross section on the back of this paper. Read all directions so that you can plan your drawing before starting to draw and label. Use a pencil to start!
1. Using the Background information as a guide, label all regions which contain
WATER.
2. Draw several (10-20) phospholipid molecules forming a lipid bilayer within the cell membrane cross section.
3. Label the polar and non-polar regions of the cell membrane.
4. Label the hydrophilic and hydrophobic regions of the cell membrane.

GROUP: ______________ DATE: _____________