Structure of the Cell Membrane
The phospholipid bilayer is selectively permeable: it
only allows certain materials to pass through.
• Only small, nonpolar, hydrophobic molecules can
pass through the phospholipid bilayer.
Can it pass through
the bilayer:
– H2O
– O2
– Proteins
Structure of the Cell Membrane
The cell membrane is made of many different
molecules, not just phospholipids.
• Fluid Mosaic Model: the cell membrane is made
of many different molecules that are free-floating
through the membrane.
• The membrane
also contains:
– Proteins
– Carbohydrates
– Cholesterol
Structure of the Cell Membrane
Proteins
• Act as channels or pumps that help move materials
across the membrane.
Carbohydrates
• Attach to the outside of the cell membrane and help
your body recognize cells.
Cholesterol
• Stabilizes the cell
membrane and keeps it
fluid at low temperatures