Cell Structure and Function

Which of the following statements about membrane proteins is true?

• All membrane proteins are peripheral
• Integral proteins are always on the surface
• Integral proteins can span the entire membrane
• Membrane proteins cannot be extracted

Human red blood cells are useful for studying the plasma membrane because:

• They are transparent
• They are large
• They lack a nucleus and organelles
• They are colorful

Which of the following best describes the structure of the plasma membrane?

• Single layer of lipids
• Rigid protein framework
• Phospholipid bilayer with embedded proteins
• Solid gel-like matrix

Cholesterol in the membrane primarily affects:

• Membrane rigidity
• Membrane thickness
• Membrane porosity
• Membrane fluidity

The hydrophobic tails of phospholipids face:

• Toward the extracellular space
• Toward the cytoplasm
• Toward the surface
• Toward the interior of the membrane