The first test that we will start with is biotest. It's a test of polypeptides. It will identify for you if you have polypeptides or protein inside the test tube. This is not a test for amino acids, only for peptide bonds. Take the appropriate amount of test tubes. Here I will test three. I will use three test tubes so you label them. One, two, three. In the first test tube I will add one ml of distilled water and this is my negative control. We are going to use dropper pipettes for this purpose. The most important thing is do not mix up dropper pipettes with each other. For each solution there is one dropper pipette because we don't want cross contamination. You cannot transfer one chemical from one place to another. The one ml is until the line of this dropper pipette. Amount doesn't have to be very specific. Just approximately one ml. My second test tube has to be a positive control, something that I know it contains protein and for this purpose I am using egg album. So with another dropper one ml still the line of egg album. And I am going to test for you milk to check if milk contains protein or not. In your experiment you will have also to check your unknown and unknown solution that you are identifying its composition. So you should have a fourth test tube in this test. Today our lab technician has prepared for us biotry agents with NAH in the same solution. So we don't need to add NAH. All what we have to do is to add one ml of the biotry agent of each of these test tubes. As discussed in the lecture a blue color is an indicator of a negative result. There are no peptide bonds and a violet color is an indicator of peptide bonds. We are going to mix our test tubes. So if you look at the negative control test tube it's a very light blue color. This is how a negative result looks like and this is the album in test tube and this is how a positive result looks like. Negative control positive control. This still water album in egg album. We look at the protein to either the milk to identify if it has protein or not. The color as you can see is closer to the positive control. It's a violet color which indicates that milk contains protein.