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General Biology lab Lab 3 Enzymes.

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Presentation on theme: "General Biology lab Lab 3 Enzymes."— Presentation transcript:

1 General Biology lab Lab 3 Enzymes

2 Definition of an enzyme
it is a biological catalyst that accelerates a chemical reaction without becoming a part of the reaction products by lowering the activation energy.

3 Structure Enzymes are generally globular proteins.
Substrates: The substances that are acted upon by enzymes. Active site : region bind the substrate into enzymes

4 General Properties of Enzymes:
Higher reaction rates . Milder reaction conditions (temp, pH, …). Greater reaction specificity (no side products). enzymes end in the suffix (ase).

5 Factors affecting enzyme activity
Substrate concentration Product concentration Temperature pH

6 Four Steps of Enzyme Action
The enzyme and the substrate are in the same area. The enzyme grabs on to the substrate at a active site. (The combination is called the enzyme/substrate complex.) A process called catalysis happens. (enzyme/products complex) The enzyme releases the product. original shape

7

8 Catalase Is an enzyme found in food as potato and liver .
It is one of the fastest enzymes in the cell that used for removing Hydrogen Peroxide from the cell. Hydrogen Peroxide (H2O2) is produced as a byproduct of many normal cellular reaction. If the cells did not break down the Hydrogen Peroxide, they would be poisoned and die. Catalase speeds up the breakdown of Hydrogen Peroxide into water and oxygen.

9 Activities Effect of temperature on catalase activity
Effect of pH on catalase activity Materials Potato H2O2 HCL NaOH

10 Procedure Effect of temperature on catalase activity: Cut 2 pieces of potato to the same size. Put the first in boiling water bath for 10 minutes, and then put it in a test tube containing 5ml hydrogen peroxide. Put the second piece (not boiled) in a test tube containing 5ml of hydrogen peroxide.

11 Effect of pH on catalase activity:
Add 2 ml hydrogen peroxide to each of 3 clean test tubes. Treat each tube as follows: Tube 1-add a drop of 1 molar HCL at time until pH 3 Tube 2-add a drop of 1 molar NaOH at time until pH 10 Tube 3-add distilled water Add a small piece of potato to each test tube

12 Amylase Is a proteinic enzyme present in our saliva, and begins to act on the starch in our food while still in the mouth . Materials Starch solution 1%. Distilled water. Saliva. Benedict's solution

13 Principle Amylase changes starch into a simpler form, the maltose which is a reducing sugar and soluble in water . benedict's solution is a test reagent that reacts positively with the simple reducing sugar like maltose, but will not react with starch.

14 Procedure Fill the beaker with water and place on the hot plate for a boiling water bath. Mark 2 test tube A and B Spit 2ml of saliva into test tube A. Into tube B add 2ml of distilled water.

15 Add 5 ml of starch solution to each tube and thump to mix .
Incubate the test tubes in warm water bath (37C) for 15 minutes. Add 3 ml of benedict's solution to each tube and thump to mix. Place the tubes in the hot water bath. The reaction takes several minutes to begin.

16 Invertase (sucrase) The man commercial source of invertase is the yeast (Saccharomyces cerevisiae). Yeast cannot directly metabolize sucrose. For the yeast to utilize sucrose as an energy source, it must first convert it to monosaccharaides glucose and fructose. The enzyme invertase catalyzes the hydrolysis of the disaccharide sucrose to glucose and fructose, which are both monosaccharaides.

17 Materials Yeast filtrate solution 1% sucrose solution
1% glucose (dextrose) solution Benedict solution Distilled water Test tubes Test tube rack

18 Procedure Label 2 test tube A1 and A2 and place in the test tube rack. Place into the test tubes as follows: Into tube A1, place 5 ml of 1% sucrose solution and 4 ml of distilled water. Into tube A2, place 5 ml of 1% sucrose solution and 4 ml of invertase extract. Thump the tubes and mix.

19 Incubate the test tubes in warm water bath (37C) for 15 minutes.
Label 2 test tubes B1 and B2 and place in the test tube rack. Place 5ml of Benedict's solution into each tube. Now transfer to the B tubes as follows: Into tube B1, transfer the contents of tube A1. Into tube B2, transfer the contents of tube A2. Thump the tubes and mix . Place tubes B1and B2 into a boiling water bath .


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