National 4/5 Biology Cell Membrane

1. National 4/5 BiologyCell Membrane

2. We are learning to: • Work together as a group • Context - Carrying out a practical experiment to find out the composition of the cell membrane • Success criteria • Everyone has a job to do • You communicate effectively • You successfully find out the components of the plasma membrane

3. Background information • Beetroot contains a red pigment in the vacuole of its cells • The cell and the vacuole are surrounded by a membrane • When the membranes are damaged the red pigment leaks out of the cell

4. Why alter the temperature? • When protein is heated to high temperatures the protein changes shape – denatured • If protein is a component of the membrane when it changes shape it will cause the membrane to become leaky and the water in the test tubes will become pink

5. Why add acid? • Acid has a similar effect on protein as temperature • When protein is added to acid the protein changes shape • Again if the acid causes the protein to change shape the membrane will become leaky causing the water in the test tube to become pink

6. Why add alcohol? • Fat/lipid is soluble in alcohol • If the membrane contains lipidthe membrane will be destroyed causing the pigment in the vacuole to escape and the water in the test tube to become pink

7. What’s the purpose of the control tube? • Tube A is the control tube • This tube will show that the membrane does not become leaky on its own • Controls show the effect of the variable being changed in an investigation

8. What do your results tell you? • Write a practical report (what should it include?) • The report should include: • Title • Aim • Method • Results table • Conclusion • Evaluation – are there any improvements or changes that could be made to the experiment

9. Plasma Membrane Plasma membrane contains protein Plasma membrane contains lipid as a bilayer