cell membrane

• cell membranes are partially permeable since they let some molecules through but not others
• membranes act as a barrier between organelles and cytoplasm
• the fluid mosaic model was suggested and consists of a phospholipid belayer and has channel proteins, carrier proteins throughout the membrane there are also receptor proteins on the membrane to detect chemical signals
• phospholipids automatically form a bilayer so the centre of the belayer os hydrophobic (tails) so no water soluble substances can diffuse through it
• cholesterol gives the cell membrane stability and fits between the phospholipids which makes the membrane more rigid
• cholesterol has hydrophobic regions
• channel and carrier proteins denature when the temperature is too low and ice crystals may pierce the membrane
• as the temperature increases the phospholipids move more because they have more energy to move and aren’t as tightly packed
• the phospholipid belayer started to break down in high temperature and the proteins denature so permeability increases
• 1. carefully cut 5 equal sized slices of beetroot and rinse
  2. add the pieces to 5 different test tubes containing 5 cm of water
  3. place each test tube in a water bath with different temperatures
  4. remove the beetroot keeping the water
  5. add to cuvette and place inside the colorimeter
  6. repeat for all the test tubes and analyse the results
  7. the more pigment released the higher the permeability