National 5 Biology Cell Membrane We are learning

National 5 Biology Cell Membrane

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

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

Why alter the temperature? • When protein is heated to high temperatures the protein changes shape • – becomes 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

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

Why add alcohol? • Fat is soluble in alcohol • If the membrane contains fat the membrane will be destroyed • - causing the pigment in the vacuole to escape • - and the water in the test tube to become pink

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

What do your results tell you? • Write a practical report (what should it include? ) • The report should include: 1. 2. 3. 4. 5. 6. Title Aim Method Results table Conclusion Evaluation – are there any improvements or changes that could be made to the experiment