Cell Structure and Function

What percentage of lipids is found in the membrane of human erythrocytes?

• 20%
• 52%
• 35%
• 40%

Biochemical investigations revealed that the cell membrane contains:

• Only lipids
• Only proteins
• Water channels
• Proteins and carbohydrates

What additional lipid is present in the cell membrane besides phospholipids?

• Sphingolipids
• Fatty acids
• Cholesterol
• Steroids

The nonpolar tails of phospholipids are protected from the aqueous environment by being located:

• On the surface
• Attached to proteins
• Inside the bilayer
• Bound to carbohydrates

In the phospholipid bilayer, the polar heads face:

• Inward
• Randomly
• Toward each other
• Outward