Biology_Lab_2_Rutgers_Newark

Abstract: Enzymes speed up chemical reactions by lowering activation energy (that is, the energy needed for a reaction to begin). In every chemical reaction, the starting materials (the Substrate in the case of enzymes) can take many different paths to forming products. For each path, there is an intermediate or transitional product between reactants and final products. The energy needed to start a reaction is the energy required to form that transitional product. Enzymes make it easier for substrates to reach that transitional state. The easier it is to reach that state, the less energy the reaction needs. Enzymes are biological catalysts. They are large protein molecules, folded so that they have very specifically shaped substrate binding sites. These binding sites make substrates go into the transition state. To catalyze the reaction, several regions of the binding site must be precisely positioned around the substrate molecules. Any change in the shape of the overall folded enzyme molecule can change the shape of the binding site. Enzymes are proteins that speed up chemical reactions in cells. They break down molecules called substrates. Each enzyme has only one substrate that it breaks down. Enzymes are produced in the cells of the body and affect the rate of almost all the chemical reactions which take place in living organisms. The rate of enzyme activity is influenced by temperature, pH, and the presence of inhibitors. Introduction Enzymes are globular shaped proteins that are found throughout the body, with their main function being to act as biological catalysts. An enzyme can act to speed up or regulate the rate of the reaction, in order to maintain an efficient rate of biological reactions. Enzymes, whilst having an important role in the reaction of many chemicals within the body, are not consumed in the reaction, and so are able to catalyze many reactions in their life cycle. Enzymes are able to reduce the activation energy of the reaction; the energy required to break bonds between the reactants, and form new bonds in the products, which allows more product to be formed. Enzyme activity is affected by changes in the pH of their solution. For each individual enzyme, there is a corresponding pH at which, that particular enzyme’s activity will be at it’s maximum. This is known as the optimum pH. If the pH of the solution is getting closer to it’s optimum pH for that particular enzyme, then the activity of the enzyme, and therefore it’s rate of reaction, will increase. At extremes of pH (either extremely acidic or basic) enzymes tend to become denatured; a state in which they lose all of their biological activity. Temperature has the ability to increase the reaction rate of chemical reactions, by increasing the kinetic energy of the molecules themselves. By increasing the kinetic energy of the molecules, there will be a greater proportion of molecules with enough kinetic energy to overcome the activation energy, and therefore form more products, this shows an increase in the enzyme activity. As the temperature increases further, the proteins become less stable, losing its shape of the activity site, and eventually becoming denatured. When the substrate concentration is increased, while the amount of enzyme is kept constant, the enzyme activity increases up until the point in which it reaches a maximum, and then no further increase in velocity will occur, even with the addition of more substrate. Unlike with changing the pH or the temperature of the reaction, adding more substrate than what is required to meet the maximum reaction rate will no cause the protein to become denatured. Materials & Methods To study the effects of temperature, pH, enzyme concentration, and substrate concentration there were certain steps that were followed in order to conduct this experiment. Each factor had a separate procedure to follow to find how each had a different effect on the enzyme. To find the effect of temperature on the activity of an enzyme, the experiment deals with the steps as follows. First, 4mL of water and 1mL of potato extract was added on a 5 test tube and placed in different temperatures 0,18,30,40,60 degrees Celsius. 1 blank test tube with 1 mL of potato extract and 6 mL of water.These three test tubes were set in three different temperature settings. The first test tube was placed in an ice-water bath for 5 minutes. The second tube’s temperature setting was at room temperature until a temperature of 18°C was reached. The third tube was placed in a beaker of warm-water until the contents of the beaker reached a temperature setting of 60° C. Sample Temp Absorbance Color Changes 1 0° C .185 Browner 2 18° C .304 Browner 3 30° C .400 Browner 4 40° C .193 Browner 5 60° C .148 Cloudy Brown To study the effects of pH on enzyme activity there were certain steps that needed to be followed also. The pH values of pH 3, pH 5, pH 7, pH 9, and pH 11 was used to fill five separate test tubes with 1 mL potato extract each. To each test tube, 2 mL of catechol , each tube was covered with Parafilm, and inverted several times to mix the contents. After letting each tube stand for three to five minutes the tubes were inverted at one minute intervals. Sample pH Absorbance Color Changes 1 3 .278 Light brown 2 5 .054 Light brown 3 7 .600 Medium 4 9 .120 Dark orange 5 11 .504 Darker orange Discussion This experiment on enzymes was done to help convey how there are environmental factors that have an effect on the activity of an enzyme. The results of these factors implied that the hypotheses are in question. For the effects of temperature, the rate of the reaction and temperature setting seemed to have an affect on the color intensity. The increase or decrease in temperature had no effect on the activity of the enzyme. In this experiment, for the effects of pH on an enzymatic activity the hypothesis was also in question. The increase in the pH level had an effect on the intensity of the color. The results showed that the lowest and highest pH levels had no color, but as the level of the pH values increased so did the intensity of color. This result was caused by the extremes of pH values, which causes denaturation and loss of enzyme activity. The effects of enzyme concentration’s results seemed to also have a different effect than the stated hypothesis. The results showed that the increase in potato juice and the decrease in pH showed to have more enzyme activity than the decrease in potato juice and the increase of pH. Enzymes are important because in digestion they speed up the break down of food for nutrients that are needed for the build up of tissues and organs in the human body. Conclusion The rate of an enzyme catalyzed reaction is not determined by a single factor, rather multiple factors including inhibitors, enzyme concentration, substrate concentration, pH, and temperatures combine to influence the rate of reaction. Many types of inhibitors affect the enzyme or substrate in a different ways to slow down the reaction. Enzymes works best at optimal pHs and an increase in temperature will result in an increase in enzyme catalyzed reaction rate until the enzyme becomes denatured.