cells and tissues

• What must the products of enzyme activity cross to enter the circulatory system?

  Plasma membranes
• What is the potential future use of artificial cells?

  As drug delivery systems or artificial blood
• What must artificial cells imitate to be viable?

  The structure and function of naturally occurring cells
• What are the main structural features of the cell membrane that need to be mimicked in a viable artificial cell?

  • Phospholipid bilayer (hydrophilic heads, hydrophobic tails)
  • Proteins embedded in the membrane (carrier or channels)
  • Glycoproteins (stability, cell recognition, signaling)
  • Cholesterol (membrane consistency)
  • Glycolipids (cell signaling and recognition)
• What is the role of protein channels in the cell membrane?

  To allow the passage of large molecules
• What is diffusion?

  The movement of a substance from high to low concentration

  
• What determines the rate of diffusion?

  The concentration gradient
• What is osmosis?

  The movement of water from low to high solute concentration
• What is facilitated diffusion?

  The movement of substances through a carrier or transport protein

  
• What is active transport?

  The movement of substances against their concentration gradient using energy

  
• What is endocytosis?

  The process where the cell membrane engulfs material to form a vesicle
• What is exocytosis?

  The expulsion of contents from a vesicle through the cell membrane
• Discuss the movement of substances in and out of cells by diffusion, active transport, and osmosis with examples.

  • Diffusion: Oxygen entering cells in the lungs
  • Active transport: Sodium and potassium ions in nerve cells
  • Osmosis: Water absorption in kidney cells

  
• Describe the fluid mosaic model of the cell membrane.

  • Phospholipid bilayer with embedded proteins
  • Allows for simple diffusion, facilitated diffusion, and active transport
  • Maintains cell integrity and function

  
• What is simple diffusion?

  The movement of a molecule across the phospholipid bilayer without special channels
• What types of substances typically move by simple diffusion?

  Small non-polar molecules like oxygen and carbon dioxide

  
• How does facilitated diffusion differ from simple diffusion?

  Facilitated diffusion uses proteins to transport molecules

  
• What drives the process of osmosis?

  The concentration of solutes within the water
• What is the role of energy in active transport?

  To move substances against their concentration gradient

  
• What are two other roles of the plasma membrane besides material exchange?

  • Acts as a physical barrier
  • Detects environmental changes using receptors