Osmosis and diffusion

• 2 components of a cell membrane

  1. Phospholipid
  2. Protein
• If an animal cell is in a solution that is the same concentration as its cytoplasm, water will move in and out at the same rate
• If an animal cell is in a solution that is less concentrated than the cell, it will gain water due to osmosis. The cell will enlarge, burst and die
• If an animal cell is in a solution that is more concentrated than the cell, it will lose water due to osmosis. It will cause the cell to shrivel and die (crenation)
• • Water - solvent
  • Chemical that is dissolved - solute
  • The mixture of these two - solution
• Osmoregulation

  The active regulation of the osmotic pressure of an organism's body fluids, to maintain the homeostasis of the organism's water content
• Turgor pressure

  The force of the cell contents against the cell wall in the plant cell
• • If a plant cell is placed in a solution that is highly concentrated, it will lose water
  • The cell membrane shrinks and pulls away from cell wall, leaving a gap between the cell wall and cytoplasm. Process - plasmolysis
• When the plant loses too much water, it also loses turgor and the plant will wilt
• Active transport

  The process where chemicals are taken into a cell against the diffusion gradient
• Active transport is undertaken by proteins in the cell membrane that drag the chemicals into cell
• Osmosis

  The movement of water from an area of high concentration to an area of lower concentration across a semi-permeable membrane
• Diffusion

  The movement of molecules from areas of high concentration to areas of lower concentration across a selectively permeable membrane
• Semi permeable

  Allows some substances to enter and some substances to leave
• Semi permeable membranes allow some substances through but not others
• Diffusion is a passive process that does not require any energy