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Objective: To be able to describe the effect of temperature to the action off enzymes towards a substrate. To demonstrate the catalytic action of enzymes.
Typology: Lab Reports
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Activity No. 8
I. Oxidase from Fruits Schematic diagram: Observation & Discussion:
Apples turn brown when exposed to the air because some of the compounds present in the apple undergo an oxidation reaction. This reaction is catalyzed by an enzyme called polyphenol oxidase (PPO). One of the reagents in this reaction is the oxygen from the air; thus, no browning reaction can start until you expose the inside of the fruit to oxygen gas (from the air). Interestingly, the enzyme PPO can only function in a range of pH’s (approximately pH 5 to pH 8); thus, you can inhibit the browning reaction by changing the pH of the apple. Foods are made up of lots of different molecules including some called enzymes. Enzymes are special proteins which can speed up chemical reactions and act as biological catalysts. They can cause fruit to ripen and over-ripen, which gives the fruit a brown colour. Oxygen in the air can cause sliced fruit to brown, a process called enzymic browning (an oxidation reaction). In addition, cold temperatures slow chemical reactions while warm temperatures speed up chemical reactions. II. Catalase A. From Potato Schematic diagram:
Un-boiled Filtrate Good bubbling ++ When the substrate of hydrogen peroxide was added to the filtrate(boiled and unboiled) each performed a slight different reaction. After dropping the Hydrogen Peroxide on the boiled filtrate samples there was a slight fizzy and bubbly reaction indicated. Once the same amount of the substrate was added to the unboiled filtrate there was a much more significant bubbly reaction. B. From liver Schematic diagram: Observation & Discussion: Chemical Equation 2H2O2(aq) ----(catalase)---> 2H2O (l) + O
In this experiment, we can infer that the liver contains the catalase enzyme while the hydrogen peroxide is the substrate. We used the liver to get a reaction from the hydrogen peroxide. The gas liberated is oxygen, we can conclude this by performing a test by re-lighting the glowing splint/match, if it lights again after extinguishing the light of the match/splint then we can conclude that the gas liberated is oxygen. III. Amylase
T2A with Fehlings’ Reagent Thick yellow precipitate T1B with 0.2% iodine solution Pitch blue black color T2B with 0.2% iodine solution Slight brown particles Based on the results test tube 1&2A using fehlings’ reagent there was no presence of red precipitates garnering negative results on test for the presence of glucose but instead a color change(Benedict's Solution) happens which indicate the presence of sugar in the solution since there is a blue and yellow precipitates. On the second set of test tube 1&2B, we had this experiment to test the presence of starch in the solution. Based on the result T1B has the prominent presence of starch in the solution having the blue black color reaction, while on T2B there is a slight color occurring or having a decrease intensity of blue black color indicating decrease amount of starch. V. ANSWERS TO QUESTIONS
A. Enzymes are proteins composed of amino acid building blocks. Enzymes catalyze or increase the rate of metabolic reactions, allowing them to occur at temperatures within the range tolerated by living cells. Thus, enzymes are an important group of functional molecules that regulate metabolic reactions in all living cells from bacteria to plants to animals. B. The enzyme amylase is a protein that acts as a catalyst which speeds up digestion of starch. In order to work well, enzymes require specific conditions including pH and temperature within specific range. Amylase is responsible for the breaking of the bonds in starches, polysaccharides, and complex carbohydrates into easier to absorb simple sugars. Salivary amylase is the first step in the chemical digestion of food.
