| Act #10: Testing for Proteins
Testing for the presence of proteins requires that we use Biuret solution. a) Scoop � cc of protein powder into a clean test tube. b) Add 2 ml of water and shake. c) What do you see? Observations: d) Add 5 drops of Biuret solution and shake. e) What do you see? Observations: f) What kinds of food contain proteins? Give me 3 examples. g) What do we need proteins for in our body? NOTE: The last of the �building blocks of life� are the nucleotides/ nucleic acids. We will concentrate on them later in molecular genetics. Act #11: pH, Measuring Acids and Bases An atom or a group of atoms may lose or gain an electron and become an ION. This simply means that it has either a positive or negative electrical charge. Acids and bases are two major groups of compounds. Each is characterized by certain ions. Acids have the hydrogen ion: H+ while bases have the hydroxyl ion: OH-. Many of the reactions, which take place in the living cell, will only occur if they are within a certain acid-base range. Remember the potato fizz experiment? We have a method of measuring how acidic or basic a solution is by means of a scale which is called pH. The pH scale ranges from 1 to 14. The lower numbers are acidic and the higher numbers are basic. Seven is neutral. 1) Why would the loss or gain of electrons change the charge of an atom? 2) What is the pH range for acids? How about for bases? 3) What pH is neutral? Act #8: Testing for pH Copy down the chart below. Using strips of pH paper and the key on the pH container, determine the pH of the following: Solution Ions in compound pH Acid/Base/Neutral Ammonia NH4+ and OH- Vinegar C2H3O2- and H+ Lime Juice C6H7O7- and H+ Lye Na+ and OH- Oil of vitriol 2 H+ and SO42- Water H+ and OH- 1) Look at your chart above. Which ION is found in all acids? 2) Which ION is found in all bases? 3) What other acids can you name? What other bases can you name? 4) Why might it be important for your stomach to maintain a pH range of 1.0 to 3.0? |