Chapter 7 Key concept review

• What model describes the arrangement of proteins in the phospholipid bilayer?


  Fluid mosaic model
• What is the role of unsaturated hydrocarbon tails in phospholipids?


  They keep membranes fluid at lower temperatures
• How does cholesterol affect membrane fluidity?


  It helps membranes resist changes in fluidity caused by temperature changes
• What are the functions of membrane proteins?


  • Transport
  • Enzymatic activity
  • Signal transduction
  • Cell-cell recognition
  • Intercellular joining
  • Attachment to the cytoskeleton and extracellular matrix
• What are glycoproteins and glycolipids, and where are they found?


  They are short chains of sugars linked to proteins and lipids on the exterior side of the plasma membrane
• Where are membrane proteins and lipids synthesized?


  In the endoplasmic reticulum (ER)
• What is the difference in molecular composition between the inside and outside faces of membranes?


  They differ in molecular composition
• What is selective permeability in the context of the plasma membrane?


  It controls the exchange of molecules and ions with the surroundings
• How do hydrophobic substances interact with the plasma membrane?


  They are soluble in lipids and pass through membranes rapidly
• What is diffusion?


  It is the spontaneous movement of a substance down its concentration gradient
• What happens to water in a hypertonic solution?


  Water diffuses out of a cell
• What occurs in a hypotonic solution?


  Water enters the cell
• What is the result of isotonic conditions for a cell?


  No net osmosis occurs
• Why is balancing water uptake and loss important for cells?


  Cell survival depends on it
• What is facilitated diffusion?


  It is when a transport protein speeds water or solute movement down its concentration gradient across a membrane
• What role do ion channels play in membrane transport?


  They facilitate the diffusion of ions across a membrane
• How do carrier proteins function in membrane transport?


  They can undergo changes in shape that translocate bound solutes across the membrane
• What are the types of endocytosis?


  • Phagocytosis
  • Pinocytosis
  • Receptor-mediated endocytosis
• What occurs during exocytosis?


  Transport vesicles migrate to the plasma membrane, fuse with it, and release their contents
• What happens during endocytosis?


  Molecules enter cells within vesicles that pinch inward from the plasma membrane