Protein & Lipid Tests PDF

Starter – 5 mins On a mini white board, describe the test for starch and the test for glucose. Did you get it right? Benedict’s test is used to test for simple Test for starch – Iodine solution sugars, for example glucose. test. 1. Prepare a sample of the food. 2. Put...

Starter – 5 mins On a mini white board, describe the test for starch and the test for glucose. Did you get it right? Benedict’s test is used to test for simple Test for starch – Iodine solution sugars, for example glucose. test. 1. Prepare a sample of the food. 2. Put 5 ml of the food sample into a test 1. Prepare the food sample tube. 2. Place a small sample of the 3. Add 5 ml of Benedict’s solution, using a food on the spotting tile. syringe, and mix. 4. Place the test tube in a water bath at 3. Add 2 - 3 drops of Iodine 80oC for 10 mins. SOLUTION to the food 5. Record the colour after 10 mins. sample. Negative result (no glucose) – blue 4. Observe the colour change. Positive results: Negative result (no starch) – Low concentration of glucose – green/yellow orange/brown Medium concentration of glucose – orange High concentration of glucose – brick red Positive result – blue/black Lesson – Testing for protein and lipids Lesson outcomes: Bronze – Recall the tests for glucose & starch. Silver – State the structure of proteins & lipids. Gold – Describe the tests for proteins & lipids. Video to help https://www.youtube.com/watch?v=13H1urX3gxI Structure of protein Proteins are polymers The monomers found in proteins are AMINO ACIDS. Proteins can be very large molecules and have very complex shapes. Proteins are used in growth & repair. They can also form enzymes – biological catalysts. (Year 10) Proteins contain the elements: Carbon, Hydrogen, Oxygen, Nitrogen and Sulphur.  Structure of lipids Lipids are made up of glycerol and three fatty acid tails. Lipids are used for insulation and protecting organs from mechanical damage. Lipids contain the elements: Carbon, Hydrogen and Oxygen. Test for Protein Biuret’s test 1. Prepare a 5 ml sample of the food. 2. Add 5 ml of Biuret’s solution. 3. Mix 4. Observe the colour change. Negative result = solution remains blue. Positive result = solution turns purple. Test for Lipid Emulsion test 1. Place a small spatula of the food sample in a test tube. 2. Add 5 ml of ethanol and shake (this will dissolve the sample). 3. Add 5 ml of water and mix. 4. Observe the result. Positive result = the solution will turn cloudy white. Negative result = the solution will remain clear.  Pestle & mortar Food testing Prepare the food sample. Place the food sample (bread) into the mortar and add a small amount of water. Then use the pestle to grind the food. Add 5 ml of water and mix. Fold the filter paper and place into a funnel. Filter the food sample (bread) into a small beaker.