Investigate the Effect of Temperature on Cell Membranes and Membrane St

Investigate the Effect of Temperature on Cell Membranes and Membrane Structure If you read a recipe for cooked beetroot it will usually recommend that you don’t remove the outer skin of the beetroot and don’t cut off al the stalk and root if you want to avoid getting lots of red dye in the cooking water. Beetroot contains red pigments called betalains, located within the cell vacuole. Normally the pigments can’t pass through membranes but they leak out when the beetroot is cooked. Aim – The aim of this practical is to use beetroot to examine the effect of the temperature on cell membranes and relate the effects observed to membrane structure. To function correctly a cell needs to be able to control transport across the partially permeable cell membrane. Theory – To understand how the red pigment leaks out of the beetroot it is essential that we understand the molecular Structure of a plasma membrane. A membrane is a phospholipid bilayer. This means that it has two layers of molecules called phospholipids. Each of these phospholipid molecules has two parts: †¢ A 'head' that will mix with water but not with fat (i.e. it is hydrophilic) †¢ Two 'tails' that will mix with fat but not with water (i.e. they are hydrophobic). In the phospholipid bilayer, the hydrophilic heads are always on the outside of the membrane. The hydrophobic tails are always on the inside of the membrane. Alone, this arrangement of phospholipids would form a barrier to water and to water-soluble substances. However, other molecules are scattered among the phospholipids. These include lipids (including cholesterol in the membranes of animals), proteins and polysaccharides. The proteins in membranes are of special interest to us. This is because they have a number of important functions. Proteins function as: †¢ Carriers for water-soluble molecules (such as glucose) †¢ Channels for ions (such as sodium and chloride ions) †¢ Pumps, which use energy to move water-soluble molecules and ions †¢ Receptors, which enable hormones and nerve transmitters to bind to specific cells †¢ Recognition sites, which identify a cell as being of a particular type †¢ Enzymes, which speed up chemical reactions at the edge of the membrane The ways that substances move across cell membrane are 1. Diffusion 2. Active transport 3. Faci... ...ees Celsius. Because at 30 degrees Celsius I would have presumed that the membrane would have been fairly stable. However my graph shows the contrary. This might be due to sources of error in my experiment. Experiments - I have successfully gained my results that back my hypothesis. However the results have limitations and some sources of error. The size of the beetroot is essential. In my experiment I used a ruler and cork bore to measure out the same size beetroot. The cork borer was a a good aid as it ensured that the beetroot had the same diameter. However using a ruler could present possible error. Due to the surface area to volume ratio. As the test tubes were taken out of the water bath and placed the in the colorimeter the temp reduced by a few degrees. This small error could of change the results by 0.5 percent inaccuracy. This is because of insufficient equipment. I understand this experiment is only on a small scale but to gain better results each test tube going up in 10 degrees Celsius so we can tell the point of denaturing more accurately, however I feel that I my experiment showed breath of how a membrane functions under temperature change.