transport

• What does the term "plasma membrane" refer to?

  Cell membranes and organelle membranes
• What model describes the structure of plasma membranes?

  Fluid mosaic model
• What does the "fluid" part of the fluid mosaic model refer to?

  Movement of molecules within the membrane
• What are the main components of the plasma membrane?

  Phospholipids, proteins, glycoproteins, glycolipids, cholesterol
• What does a partially permeable membrane allow?

  Only certain molecules to diffuse through
• What charge does the phosphate group in the phospholipid head have?

  Negative charge
• What is the arrangement of phospholipids in the bilayer?

  Hydrophilic heads face outside, tails inside
• Why are fatty acid tails considered hydrophobic?

  They do not have any charges
• What distinguishes saturated fatty acids from unsaturated fatty acids?

  Saturated has no double bonds; unsaturated does
• What role does cholesterol play in the membrane?

  Restricts lateral movement of molecules
• What happens to membranes at high temperatures without cholesterol?

  They become too fluid, risking leakage
• What are the two types of membrane proteins?

  Peripheral and integral proteins
• What is the function of peripheral proteins?

  Provide mechanical support and connect molecules
• What do integral proteins do?

  Span the entire width of the membrane
• What is a glycoprotein?

  A protein with a carbohydrate attached
• What is the function of glycoproteins and glycolipids?

  Serve as recognition sites, like receptors
• How do channel proteins function?

  Allow water-soluble ions to diffuse through
• What do carrier proteins do?

  Transport larger molecules by changing shape
• What does "partially permeable membrane" mean?

  Only certain molecules can diffuse through
• Which types of molecules can diffuse through the phospholipid bilayer?

  Lipid-soluble and very small molecules
• Which hormones can diffuse through the membrane?

  Estrogen and small gas molecules
• What types of substances cannot pass through by simple diffusion?

  Larger water-soluble and polar substances
• What are the key features of the phospholipid bilayer?

  • Composed of two layers of phospholipids
  • Hydrophilic heads face outward, hydrophobic tails inward
  • Forms a barrier that is selectively permeable
• What are the roles of cholesterol and proteins in the plasma membrane?

  • Cholesterol:
  • Restricts lateral movement
  • Maintains membrane fluidity at high temperatures
  • Proteins:
  • Peripheral: Provide support and connect molecules
  • Integral: Transport molecules across the membrane
• What is the significance of the fluid mosaic model?

  • Describes the dynamic nature of the membrane
  • Components can move laterally
  • Allows for flexibility and functionality of the membrane
• What types of molecules can pass through the plasma membrane and how?

  • Lipid-soluble molecules: diffuse freely
  • Small molecules: diffuse through gaps
  • Larger molecules: require transport proteins
• Who is the instructor in the video on transport across membranes?

  Miss Estrich
• What does the video on transport across membranes follow from?

  The video on cell surface and organelle membranes
• What can simply diffuse through the phospholipid bilayer?

  Lipid-soluble molecules
• Why can't water-soluble or polar substances simply diffuse through the phospholipid bilayer?

  They are not lipid soluble
• What is the first type of diffusion discussed in the video?

  Simple diffusion
• What is the net movement of molecules in simple diffusion?

  From higher concentration to lower concentration
• What happens when equilibrium is reached in simple diffusion?

  Concentration is the same on both sides
• Does simple diffusion require ATP?

  No, it does not require ATP
• What type of energy do molecules possess to enable diffusion?

  Kinetic energy
• In which states of matter does simple diffusion occur?

  Liquids and gases
• What type of molecules can diffuse across the membrane?

  Small and lipid-soluble molecules
• What is the second type of diffusion mentioned?

  Facilitated diffusion
• How does facilitated diffusion differ from simple diffusion?

  It uses proteins embedded in the membrane
• What types of molecules typically use facilitated diffusion?

  Polar molecules and large molecules