Writing Lab Report 3 Understanding the Mechanisms That Control the Rates of Enzymatic Reactions

Contents of Lab Report 3  Title (on a cover page)  Purpose and subject of experiment  Please also include: author, collaborators, lab section, date  Abstract  One-paragraph summary of  question studied  short description of experiment  results  conclusion

Contents of Lab Report 3  Introduction  Background for the question you are studying  Hypothesis or Statement of Findings/Conclusion regarding the effect of your independent variable on the rate of an enzymatic reaction  Be sure to identify two measurable variables and the predicted relationship between them as shown in Figure 2  All information should be consistent with known characteristics of enzymes  You should consult references beyond your text and lab manual for information to include in the introduction

Contents of Lab Report 3  Introduction  Types of resources to consult  General biochemistry text  In print: books to check out from SMC library or from Dr. Colavito  Online: see links on Dr. Colavito’s homepage  Primary literature on enzyme activity, including research on phenolase/tyrosinase in potatoes or other organisms  Use online databases to find articles  Use Google Scholar to access full length articles

Contents of Lab Report 3  Materials and Methods  Describe how the experiment was conducted, giving enough detail so that another scientist can duplicate your method  Specify only materials and procedures that are unique to the experiment, rather than those used routinely by all scientists  Include only specific information about your experimental approach, do not include general information from the lab manual regarding preparing the potato extract or the initial laboratory session testing many variables.  Write in the past tense to show that the experiment has already been completed, rather than as a list of instructions to follow

Contents of Lab Report 3  Results  Two Figures (graphs) with proper captions  You may include additional figures if appropriate for your experimental design  Text that briefly describes the contents of the figures (see Student Handbook by Knisely, p. 38)  Introduce the reader to the way in which you are presenting the data  Describe what you expect the reader to notice about each figure, identify patterns/trends observed

Results: Figure 1  Use Excel to plot absorbance versus time for all six experimental and/or control samples. If the curves overlap and form a confusing pattern, you may present the data in two or more graphs.  Superimpose a smooth curve  Label the axes appropriately, indicating the x and y variables and their units of measure  Provide a caption below the figure  title  brief description, that can include  source of the data  legend for symbols used in the graph—be sure the reader can distinguish between the six different samples studied  relationship observed, including equation for trend curve or line  how the figure will be used in the results and/or discussion sections

Example of Figure 1 with Fictitious Data Figure 1: Progression of enzymatic reaction at varying substrate concentrations. Yellow triangle = substrate concentration 5, purple circle = substrate concentration 4, green x = substrate concentration 3, blue diamond = substrate concentration 2, purple x = substrate concentration 1, pink rectangle = no substrate added. For Figure 2: Take the slope of each curve at an early time interval and plot each slope against the corresponding value for the independent variable (in this case the 1-2 minute interval was chosen).

Results: Figure 2  Choose ONE, early, time interval and determine the slope of each curve in Figure 1 for that time period. You may choose any consistent method for determining the slope, including making calculations from the Excel-generated equation for the Figure 1 curve or taking the first derivative of the Figure 1 curve.  Use Excel to plot the slope (Rate of Enzyme Activity) versus the independent variable you are studying.  Superimpose a smooth trend line or curve  Label axes appropriately, indicating the x and y variables and their units of measure  Provide a caption below the figure

Example of Figure 2 with Fictitious Data Figure 2: Rate of enzyme activity versus substrate concentration. Rate values were calculated as slopes from the trendlines in Figure 1.

Contents of Lab Report 3  Discussion  Present an integrated INTERPRETATION of results as they relate to the question you are studying  Propose and analyze a MECHANISM that would match the relationship shown in each figure  Describe how well the data fits each proposed mechanism, including a BRIEF error analysis  Relate your results to what is known about enzymes in general or phenolase specifically, using information from your references  Conclusion  Give an overall summary of the relationship between your independent variable and rate of enzyme activity, indicating whether the data you collected support the expected relationship

Contents of Lab Report 3  Literature Cited  Use name-year system for identifying references within the text  eg. The data are consistent with the effects of a noncompetitive inhibitor of phenolase (Yoruk and Marshall, 2006).  Use APA style to list references under Literature Cited [preferred method even if article was accessed online]  Yoruk, R. and M.R. Marshall A Survey on the Potential Mode of Inhibition for Oxalic Acid on Polyphenol Oxidase. Journal of Food Science 68:

Contents of Lab Report 3  Literature Cited (continued)  Citing the Lab Manual  Logan, R Enzymatic Reactions. Biology 21 Lab Manual. Santa Monica College.  For a reputable website, give and date accessed  Accessed 10/14/08.

Suggested Writing Order  Materials and Methods  Results  Discussion  Introduction  Abstract  Title Page  References

Collaboration  You may DISCUSS any aspects of your lab report with fellow students and/or your instructor  You must PRODUCE the figures and WRITE your lab report independently  Any unusual similarities will be addressed according to the SMC Code of Academic Conduct. Everyone involved will lose full credit for their reports. There are no makeups for lab reports showing academic dishonesty.