Structure and function of membranes

• What is the function of membranes in cells?

  They produce different compartments inside cells
• Why are membranes important in cell signaling?

  They allow electrical signals to pass along them
• What do membranes provide for enzymes?

  Attachment sites for enzymes
• What is compartmentalization in cells?

  Formation of membrane-bound areas in a cell
• What does the plasma membrane separate?

  Components of the cell from their environment
• What is the role of the phospholipid molecule in membranes?

  It forms a bilayer in plasma membranes
• Why do phospholipids form a bilayer?

  Polar phosphate groups face aqueous solutions
• What happens to the fatty acid tails in the bilayer?

  They move away from the aqueous environment
• How do hydrogen bonds affect the phospholipid bilayer?

  They hold the two layers together
• What effect do saturated fatty acids have on membrane fluidity?

  They make the membrane less fluid
• How does temperature affect membrane fluidity?

  Warm temperatures make membranes more fluid
• What does the fluid mosaic model describe?

  Structure of membrane with proteins and lipids
• What are the two types of proteins in cell membranes?

  Intrinsic and extrinsic proteins
• What do intrinsic proteins do?

  They completely span the bilayer
• Where are extrinsic proteins located?

  On the surface or partly embedded in the membrane
• What are glycolipids?

  They are lipids with carbohydrate attached
• What role does cholesterol play in membranes?

  It helps maintain membrane fluidity
• How do polar molecules pass through the membrane?

  They require proteins to pass through
• What is the significance of the phospholipid bilayer's structure?

  It allows lipid-soluble molecules to enter and leave
• What does the bilayer prevent?

  Water-soluble molecules from entering and leaving
• How does the fluid mosaic model differ from earlier models?

  It incorporates experimental and chemical evidence
• What is the role of proteins in the fluid mosaic model?

  They are distributed unevenly throughout the membrane
• What is required for polar molecules to pass through the membrane?

  Proteins to facilitate their passage