Enzymes: They Are All Around You

Biology Enzymes Name: ______Period: ___ Date:______

VIDEO: Brainpop and Enzymes (http://youtu.be/CZD5xsOKres) 1. After watching the videos on enzymes, describe in your own words what an enzyme is.

2. Why do you need enzymes?

ENZYMES: YOU CAN’T LIVE WITHOUT THEM! PART I: Background Information

All living things have mechanisms that allow them to maintain a stable internal environment. Without these mechanisms organisms can die. The maintenance of internal conditions is known as homeostasis. Organisms have regulatory systems that maintain internal conditions, a large part of which are enzymes that reduce the amount of energy needed by cells for chemical reactions to take place. Without the aid of enzymes, an organism’s metabolism (the sum of all the chemical reactions within the organism – including the breakdown and build up of molecules) would occur too slowly to sustain life.

Fill in the chart in your notes with the

Enzymes are a class of proteins, which are able to aid in the completion of chemical reactions. Enzymes are known as catalysts. Catalysts increase the rate of chemical reactions, without which the reaction would occur very slowly. Enzymes are highly specific in their catalytic activity, meaning that certain enzymes work with certain substrates (the substance being acted on by the enzyme – example – fat molecules are the substrate for the fat enzyme). The reason that they are said to be so specific is because the enzyme and substrate fit closely together. The three-dimensional fit of the enzyme-substrate complex helps chemical reactions occur by lowering the energy needed to complete the joining or breaking of the substrate to make the desired products. Once the chemical reaction is complete, the enzyme and substrate separate. The substrate has changed during the reaction, but the enzyme remains the same allowing it to react with another substrate until all the substrate has been changed into the desired product.

3. Explain what happens to the enzyme and substrate after the chemical reaction has taken place. ______

Enzymes are very sensitive proteins. An enzyme’s three-dimensional shape is due to weak bonds between amino acids that cause the folding and twisting of the Biology Enzymes Name: ______Period: ___ Date:______amino acids chain that comprises the enzyme. These weak bonds can be broken by changes in pH and temperature. Under harsh conditions such as extreme temperature and pH levels, the enzyme becomes denatured, or inactive. Once denaturing occurs the enzyme is no longer able to fit with the substrate and acts as a catalyst for chemical reactions. Depending on its location in the body, each enzyme has an optimum pH and temperature at which it works best.

Answer the following in completely. 4. What are the subunits or building blocks of enzymes? ______5. What happens to an enzyme under harsh conditions? ______6. What is meant by an enzymes optimum temperature? ______

Starches are complex carbohydrates that are found in food such as rice, potatoes, bread and crackers. Digestion of carbohydrates, such as starches, begins in your mouth when it mixes with your saliva. The digestive process is completed in the small intestine. Amylase is an enzyme found in saliva that breaks down starches into simple sugars. (Just as with amylase, most enzymes end in the suffix “ase”). Amylase is a catalyst, because it causes a chemical reaction to take place quickly without being changed by the reaction. That very same enzyme will do the same thing the next time a starchy food is eaten. Without enzymes such as amylase, our metabolism would occur too slowly to sustain life.

7. The amylase enzyme found in ______breaks ______down into ______. 8. How could our metabolism be affected if there were no enzymes? ______

PART II: KNOW YOUR PH Biology Enzymes Name: ______Period: ___ Date:______pH is one of the factors that can influence an enzyme’s ability to function. The pH of a substance also has a tremendous affect on its properties. For instance, you wouldn’t drink vinegar to calm an upset stomach or use soap to dissolve metal. Vinegar is an example of an acid, whereas the chemicals in soap are mostly bases. An acid is a substance that typically tastes sour and a base is a substance that can leave a slimy or soapy feeling on your fingers. pH is the measure of the acidity of a solution. Examine the pH scale. Acids are found from pH 0 – pH 6.99. pH of 7 is neutral, and a pH of 7.01-14 is bases.

JUST REMEMBER: A goes with B Acids are Below 7 Bases are Above 7

9. Which is more acidic, stomach acid or tomatoes? ______

10. A substance with a pH of 8.7 is a(n) ______

11. Which substance is closest to neutral; black coffee (pH 4.8), human saliva (pH of 6.9), baking soda (pH of 9) or oven cleaner (pH of 13)? The substance closest to neutral is ______.

12. If a student measures the pH of stomach acid and the pH of oven cleaner the pH of stomach acid would be (above / below) 7, but the pH of oven cleaner would be (above / below) 7.

13. What is the weakest acid listed on the diagram? ______

14. What is the pH of the strongest base listed on the diagram? ______

ANALYSIS

15. What temperature and pH does amylase work best at? Explain ______

16. Rain water has a pH of 5.8, is it acidic or basic? Explain your answer. ______EXTENSION Biology Enzymes Name: ______Period: ___ Date:______

17. What is the pH of pure water? With that in mind, do you think the pH of body fluids (sweat, blood, saliva, urine etc) is mostly acidic, mostly basic or mostly neutral? Explain why. ______

Enzyme Shapes: Read and Answer the questions Enzymes are proteins that act as catalysts in living cells. Enzymes are also very “picky” molecules and only work on one substrate.

1. The substrate for a particular reaction is shown below. In the box labeled “Enzyme,” predict the shape of the enzyme that will react with this substrate. Draw the enzyme in the space provided.

SUBSTRATE ENZYME 2. Explain the significance of the shape of the enzyme that you just drew.

3. In the box below, predict the shape of the enzyme AFTER the reaction has taken place. Draw it in the box below. Explain your prediction in the space provided.

 ENZYME AFTER REACTION

4. In the box below, predict the shape of the substrate AFTER the reaction has taken place. Draw it in the box below. Explain your prediction in the space provided.

 SUBSTRATE AFTER REACTION