t2 transport across membranes

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


  Cell membranes and organelle membranes
• What does the "fluid" part of the fluid mosaic model refer to?

  Movement of molecules within the membrane
• What model describes the structure of plasma membranes?

  Fluid mosaic model
• What are the main components of the plasma membrane?

  Phospholipids, proteins, glycoproteins, glycolipids, cholesterol
• What creates the partially permeable nature of the membrane?

  Properties of phospholipids
• How many layers make up the phospholipid bilayer?

  Two layers
• What orientation do the hydrophilic heads of phospholipids have?

  Facing the outside of the bilayer
• What is the charge of the phosphate group in the phospholipid head?

  Negative charge
• Why are fatty acid tails considered hydrophobic?

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

  Presence of a double bond between carbon atoms
• What role does cholesterol play in the plasma membrane?

  Restricts lateral movement of molecules
• How does cholesterol affect membrane fluidity at high temperatures?

  Reduces fluidity, making it more rigid
• 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 the function of glycoproteins and glycolipids?

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

  Allow water-soluble ions to diffuse through
• What happens when larger molecules bind to carrier proteins?

  Causes the protein to change 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 molecules and small gases
• What is an example of a molecule that cannot pass through by simple diffusion?

  Glucose
• Why can't sodium ions pass through the membrane by simple diffusion?

  They are larger than water molecules
• What are the key components and functions of the plasma membrane?

  • Phospholipid bilayer: forms the membrane structure
  • Cholesterol: regulates fluidity and stability
  • Proteins: transport molecules and provide support
  • Glycoproteins and glycolipids: serve as recognition sites
• How do the properties of phospholipids contribute to membrane function?

  • Hydrophilic heads face outward, attracting water
  • Hydrophobic tails face inward, repelling water
  • Creates a barrier for water-soluble substances
  • Allows selective permeability for certain molecules
• What are the roles of integral and peripheral proteins in the membrane?

  • Integral proteins: span the membrane, transport molecules
  • Peripheral proteins: provide support, connect to other molecules
• What is the significance of membrane fluidity?

  • Allows movement of proteins and lipids
  • Essential for cell signaling and transport
  • Maintains membrane integrity at varying temperatures
• Who is the instructor in the video on transport across membranes?

  Miss Estrich
• What is the focus of the video by Miss Estrich?

  Transport across membranes
• What type of molecules 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 cannot pass due to their properties
• 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 characteristics must molecules have to diffuse across the membrane?

  They must be small and lipid soluble
• 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