First briefly and clearly state how well your

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Unformatted text preview: the lab notebook, but will not be graded. These items need to be prepared separately for each question. 1) Results. Begin by preparing the required graphs (if any) and then doing the required calculations. Next prepare a simple table of your processed data (e.g. the different rates for the different experimental conditions). Once the table is prepared, you then need to provide a brief statement describing what the table shows. Do not make interpretations of your results at this time. 2) Discussion. For each question you need to do the following. First, briefly and clearly state how well your predictions and results matched (be sure to mention the data that supports your claim). In the case of a good match, conclude with a simple declarative statement of what was learned this should be expressed in the terms of your hypothesis. In the case of a poor match, describe what you think went wrong and propose the specific changes that you think would improve your results were you to perform the experiment again. These changes may be to the manner in which you performed the experiment or to your original hypotheses. *** Biology 05LA – Fall Quarter 2012 Lab 4 – page 6 The questions that will be addressed by the experimental labs this quarter are listed below or within the relevant lab exercise. The Enzyme Lab. 1) How will increasing substrate concentration affect the rate (v0) of an enzymatic reaction if the enzyme concentration is held constant for the different trials? 2) How will altering pH affect the rate (v0) an enzymatic reaction? The Fermentation and Respiration Lab – these will be presented with the lab exercise. Learning Goals/Desired Outcomes 1) Be able to define and differentiate between the following pairs of terms: a) inductive reasoning – deductive reasoning. b) hypothesis – prediction. (an “educated guess” will not be considered as an adequate definition of a hypothesis!) c) experimental protocol – experimental strategy. 2) Be able to explain why gaining a thorough knowledge of the known facts related to a particular question is a vital prerequisite to proposing a hypothesis for that question. Biology 05LA – Fall Quarter 2012 Lab 5 – page 1 LAB #5: ENZYMES Enzymes are organic catalysts that participate in the chemical conversion of one organic molecule to another. The molecule that is acted upon by an enzyme is known as its substrate and the molecule that is formed by the reaction is called its product. Enzymes participate in these reactions without being chemically changed as they are completed. Thus, one molecule of an enzyme could theoretically catalyze many conversions of substrate to product. This recycling of enzyme in multiple conversions of substrate to product is referred to as the catalytic cycle of an enzyme. It is described in the box to the right. When enzymes were first discovered, they were E+S ES EP E+P given a wide variety of names. For example, the enzyme that initiates the digestion of starch in the mouth, salivary The catalytic cycle of an enzyme occurs in 3 steps. amylase, was called ptyalin. Currently, enzymes are The enzyme and substrate bind to form an enzymenamed systematically by what they do. The ending "ase" substrate complex . While bound to the enzyme, the identifies a substance as an enzyme. This ending is substrate is converted to product resulting in an preceded by a stem which indicates a specific substrate, enzyme-product complex. The product is then released and the enzyme if free to bind another substrate molecule. the general nature of the substrate, or the type of action catalyzed by the enzyme. For example, succinic dehydrogenase removes two atoms of hydrogen from succinic acid, while hydrolases insert a molecule of water across a bond and thereby hydrolyze a compound. Most enzymes are proteins and are sensitive to environmental conditions. Enzymes, like most proteins, can be irreversibly damaged or denatured by high temperatures or pH extremes. There are a number of fascinating exceptions to these general rules: enzymes whose critical component is not protein, enzymes from organisms that thrive in super-heated ocean volcanic vents, and enzymes that operate quite well at very acidic or alkaline conditions normally viewed as deadly for all life. All enzymes, even the unusual ones, have conditions of temperature, pH, and concentrations of enzyme and substrates that promote their most efficient activity. In today's exercises, we will examine the activity of bovine intestinal alkaline phosphatase when exposed to variations in two of the above parameters. This enzyme normally operates in the intestines of cattle, away from the acidic stomachs (cattle have more than one), breaking down a variety of phosphorylated compounds found in their food. Alkaline phosphatase can hydrolyze the artificial substrate p-nitrophenylphosphate, giving us a convenient way to make quantitative measurements of its activity under different conditions. The basis for this convenien...
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