Transporting of molecules

• Diffusion


  Passive movement of particles from a region of high concentration to low concentration
• Diffusion 


  Passive process

  Membrane is not essential

  Multiple types of diffusion
• Facilitated diffusion 


  Passive movement of either large molecules (glucose) or ions(calcium) moving from high concentration to low concentration using either a channel or carrier protein
• Facilitated diffusion 


  Carrier protein carry molecules which are larger. E.g glucose, amino acids

  Channel protein are concerned with transporting ions through membranes. E.g ions
• Active transport 


  Movements of a substance across a membrane using energy

  ATP is produced by respiration

  From a region of low concentration to high concentration

  Protein pumps in the membrane are used for active transport
• Osmosis 


  Diffusion of water

  Passive process

  Membrane is essential
• Hypertonic 


  Lots of solute, low water

  Water moves out of tissue
• Hypotonic 


  Less solute, more water

  Water moves into tissue
• Isotonic 


  Equal osmolarity/solute

  No net movement of water
• Application of osmosis 


  Tissues or organs to be used in medical procedures must be bathed in a solution with the same osmolarity as the cytoplasm to prevent osmosis
• Assisting osmosis 


  -Some cells contain protein carriers to increase rate of diffusion.

  -similar to carrier proteins, called aquaporins

  -Only allow water through

  -Positive charge to stop any H+ ions passing through

  -lots of aquaporins in the kidney
• exocytosis and endocytosis 


  -Sometimes substances need to be moved into or out of a cell that can’t be done by diffusion or active transport

  -usually larger substances

  -rely on the fluidity of the plasma membrane
• Exocytosis


  -Vesicles containing the material to be expelled moves to the plasma membrane

  -the vesicles fuse with the plasma membrane

  -vesicles then opens to the exterior of the cell, releasing its contents out of the cell

  -uses ATP/energy
• Endocytosis


  Sometimes larger molecules need to be taken into the cells

  -phagocytosis: large solid particles-pathogens, immunity

  -pinocytosis-liquids
• Water potential 


  Measure of the potential energy per unit volume of water
• Water potential 


  Water potential = solute potential + pressure potential
• What are the two types of transport processes mentioned?

  • Passive transport
  • Active transport
• What is required for active transport?

  Energy
• What is the direction of movement in passive transport?

  With the concentration gradient
• What is the direction of movement in active transport?

  Against the concentration gradient
• Does facilitated diffusion require energy?

  No
• What type of transport is osmosis classified as?

  Passive transport
• Does osmosis require energy?

  No
• What is the role of aquaporins in osmosis?

  Aquaporins facilitate the movement of water
• What is endocytosis?

  A process where cells engulf substances from the outside
• What is the origin of life mentioned in the study material?

  The study material does not provide specific details on the origin of life
• What are the characteristics of passive transport?

  • No energy required
  • Movement is with the concentration gradient
  • Includes processes like diffusion and osmosis
• What are the characteristics of active transport?

  • Requires energy
  • Movement is against the concentration gradient
  • Includes processes like endocytosis and active transport mechanisms
• What is facilitated diffusion?

  • A type of passive transport
  • Requires specific transport proteins
  • Does not require energy
• What is cytosis?

  • A process involving the movement of large molecules
  • Can be endocytosis (into the cell) or exocytosis (out of the cell)
  • Can involve aquaporins for water transport
• Summary of the transporting of molecules