Biochemistry Lab Guidelines

Contents

NOTE: SPECIFIC ASSIGNMENTS FOR EACH REPORT ARE PROVIDED AT THE END OF EACH LAB HANDOUT.

Laboratory Reports

You will work with a partner or group to collect data. You will then prepare your own lab report.

You must hand in PRINTED reports. I will not accept computer files or email reports.

All components of reports should be of high quality, as if for inclusion in a published paper.

The written sections of all reports should be an example of your best writing, prepared with the same care you would take in a writing course. Your ideas should be clear and insightful; your paragraphs should be organized, coherent, and in sensible order; your sentences should be logical and grammatically correct; your words should be thoughtfully chosen and correctly spelled. Write in first person, active voice, past tense ("I digested lysozyme with trypsin... .") Deficiencies in these areas will result in rejection of the Report. Throughout the report, speak of the work and the results as if it were research having value in itself; do not describe the work as a course experiment with educational goals.

For Emphasis: All components of your report should be your own work. For example, if you and your partner submit identical graphs, with identical scales, labels, and titles (not likely if you both produce your own), then you will each receive only half of the credit that the graph earns.

One week after the scheduled completion of each lab project, submit a Laboratory Report, following the instructions in the lab handout or in the Report Assignments, which are included each lab handout.

Here is more information about report components that may be requested in each report (most reports will not have all parts):

  1. Completed laboratory report sheets, if provided. After you have collected the data (in your lab notebook) and completed all the required calculations and graphs for the experiment (also in your notebook), photocopy the Laboratory Report Sheet from the handout and transfer your results neatly onto the photocopies.
  2. Tables, if requested. Produce tables with a spreadsheet or the table tool in your word processor. Lay out and label rows and columns as requested. Give the table an informative title.
  3. Graphs, if requested. Produce all graphs with a computer program like Excel. Give each graph a title that informs the viewer of the relationship shown on the graph. Name the variables on the axes and specify their units -- for example: DNA Marker Length (bp). Graph all quantities in the units requested. I will not try to figure out results in other units. Using the title and axis labels, try to tell the reader as much as possible about the graph's meaning. More.
  4. Sample calculations, if requested*. Show clearly each calculation, either on the back of the page where the calculated result is shown, or on a page inserted immediately after the calculated result. Number all calculations the same as the number of the calculated result. For repetitive calculations, give one sample. Show the units of all quantities including the result, and report quantities to the proper number of significant digits.
    * If calculations in your lab notebook fully satisfy this requirement, refer me to the specific page in your notebook. This is the only report component for which you can substitute lab-notebook sheets.
  5. Figures, if requested. Use a computer drawing program to make a publication-quality drawing. Label parts of the figure clearly. Include an informative title. Using the title and labels, try to tell the reader as much as possible about the figure's meaning.
  6. Interpretation, if requested. One page maximum. Discuss the molecular models and mechanisms that explain the behavior of the substances under study, and then explain the meaning of your own specific results, including your final calculated values or graphs, in molecular terms. Also discuss any significant deviations from expected results and tell a) the basis of your expectations, and b) why you believe such deviations occurred. The most important part of the interpretation is to demonstrate that you understand the molecular basis for your results. In many cases, this will require chemical equations and structures.
  7. Answers to study questions, if provided. Entitle the section Study Questions. Answer questions in complete sentences.
  8. Lab-notebook copy sheets, always. Attach lab-notebook copy sheets for this project to the back of your report. Be sure that I can find in these pages all calculations on which report results are based. Remember that your notebook entries should be completed BEFORE you begin preparing the report and that they are not a part of the report, so do not refer to them in the report, and do not use them as a substitute for any part of the report (one exception: sample calculations). They are primarily for evaluation of your record-keeping.

YOUR REPORT SHOULD INCLUDE ONLY THE ITEMS REQUESTED. Please help me by stapling the parts together in the order listed in individual report instructions.

Laboratory Notebooks

Keep a laboratory notebook in somewhat the same manner required in CHY 252/254, using the Chemistry Department approved lab notebook (available at bookstore). Following is a modified version of Tom Newton's guidelines. You will hand in notebook sheets for each project along with the report. I will evaluate your entries and make suggestions about how to keep more useful records of your lab work. Your grade for the lab notebook will be based upon the kind of records you are keeping in the latter part of the semester, after you have had a chance to correct earlier deficiencies, if any.

You must have a bound laboratory notebook that produces a carbon copy of each page as you work. Your instructor will show you the approved notebook for chemistry courses. When you begin a new project, start on a new page, and list it in the Table of Contents. Give dates of all work -- begin each session of lab work by entering the date in the notebook. If you think that the timing of steps may be important, enter the time you begin each important operation.

It is not acceptable to keep notes -- any notes -- on scrap paper. Your notebook is your scrap paper. It is not supposed to be a work of art. It should contain all the information that is necessary for you or any person with similar background to reproduce the experiment that you performed, along with thorough records of what you observed as you proceeded. This is the primary criterion for a good notebook: it contains enough detail that someone unfamiliar with the experiment can perform it by following your notes, using your observations to help them see if all is going well. You should develop the habit of recording your notes at regular intervals throughout the afternoon. It is not acceptable to work from 1:30 until 5:00 PM and then try to summarize your day's work -- too much detail is lost. Of course, your writing must be legible. If you are working with a partner or team, keep your OWN, COMPLETE records and insist that your partner does also. Do not plan to share lab notes later.

After lab, and on your own, carry out your preliminary and final calculations and graphing in the notebook, and then transfer graphs, final calculations, or sample calculations to the report as you write it. If you use computer spreadsheets or graphing programs, make a copy for your notebook, as well as for your report, and attach final graphs and spreadsheets in the notebook (two copies). When you are ready to write the report, write your major conclusions in the notebook in an informal "conclusions" section. With these tasks completed, you are ready to prepare the report. Writing the report should be mostly a matter of organizing entries taken from your notebook. If you follow these guidelines, your notebook can stand alone (without the report) as a record of your work during and after lab.

Write all your notes in the first person, past tense, active voice. In formal presentations, many uninformed scientists still write in third person, past tense, passive voice. This style is no longer acceptable even in formal writing, and is certainly not acceptable for informal notes. Record your notes in ink. If you make an error, cross it out with a single stroke. Do not erase or obliterate your mistakes.

Grading the Notebook

Factors that affect your notebook score are completeness, clarity, and legibility. Completeness means that your notes not only describe what you did (to the bitter end of your final calculations, results, and conclusions), but they also record your observations of what happened as a result of your action(s). One of the most common deficiencies in lab notebooks is the failure to record observations.

Appendix I: Special Note About GRAPHS

 

A graph should be able to stand alone as a description of a chemical system and its behavior. Follow these guidelines for all graphs:

  1. For most graphs, the graph type should be scatter, with data markers shown, with no connecting line or curve. A connecting line or curve obscures data, and can obscure a fitted line added later (see last guideline in this list). Connecting curves or lines are appropriate only when the data are a series of measurements that are not expected to be linear or to fit some simple mathematical function. This kind of plot is generally referred to as a chart, rather than a graph. Examples: A calibration curve is a graph. A chromatogram is a chart.
  2. Include the origin (0,0) at the lower left of the graph, if practical.
  3. Scale the graph so that the data occupies most of the displayed graph area.
  4. Label the axes with variable names, followed by abbreviations of units of the variable in parentheses: Example: Concentration of S2O82- (mol/L).
  5. Divide the axes into easy-to-understand units.
  6. Give an informative title that adds to the information on the axes. Example, for a graph of rate constant versus temperature: Effect of Temperature on Rate of Oxidation of Iodide Ion by Peroxydisulfate. The title should not simply reiterate the names of the variables; they are obvious to the reader if the axes are properly labled. Again, for emphasis: Do not repeat the axis labels in the title.
  7. Display the equation of a line or curve fitted to the data (if applicable). Edit the equation to change the default variable names (usually x and y) to the actual names of the variables you graphed. If there is a fitted line or curve, do not have the data connected by lines or curves.

Here is an example of a graph that meets all requirements:

CHY 462 Syllabus