KE0026 Biochemistry Labs

How to write a lab report

During this course you will perform several laboratory experiments and tutorials that should be presented in lab reports. This page describes general outlines for how such a report may be written. It is advisable that you read this page several times during the course. Hopefully this will help you to improve your writing skills.

Do not forget that you are writing an accurate account of what happened for anyone who wishes to read your report, not just the teacher who will mark it. You should be able to give your report to a friend who has never seen the practical manual and he or she should be able to follow what you did and what your results were, assuming they have some basic knowledge in the subject.

The report should contain your results, how you achieved them, and an evaluation of the results. You should demonstrate that you have understood the experiment as well as how to document and present it. Try to keep the text as short as possible without leaving out important information or using a poor language. This is a difficult task but practice makes perfect.

The layout is important for a good final result, hence the report should be computer written with a word processing program. A recommended font is e.g. Times New Roman. Figures should be constructed with the aid of a computer program. Computer made figures are added directly in the text if it is possible to reduce them to a suitable size. The report is much easier to read if you don't have to flip back and forth between the main text and an appendix. Remember that figures must be numbered, have a legend and be referred to in the text.

Lab reports may be written in either Swedish or English. If you write your report in Swedish, the abstract should still be in English. Normally you leave one report per two persons i.e. one report per lab group even if some of the experiments were made in larger groups. Each of the two persons handing in a joint report is individually and fully responsible for the whole lab report. Reports may also be written individually. Make sure to keep your copy of the report at least until you have passed the course.

Generally, lab reports should include the following sections, as in the usual outline of a scientific paper. During the course you will perform both 'wet' laboratory experiments as well as computer tutorials. In the latter case some minor changes may be made from the general rules according to specific instructions given in connection to the tutorial.

Front page
The front page contains title of the laboratory experiment/tutorial, your name(s), group (A, B...), name(s) of the teacher(s), and the date you made the experiment as well as the date you hand in the report.

Abstract
The abstract should give a brief (5-10 lines) summary of the entire report i.e. the purpose of the lab, the methods you used, and the results you have achieved. This is the section in a scientific article where you are supposed to get the reader interested in the subject.

The abstract should always be written in English, even if the rest of your report is written in Swedish.

Common errors:
The abstract is sometimes completely left out.
Results and conclusions are missing from the abstract

Introduction
In the introduction you supply the reader with some basic background which is important to allow the work to be placed into perspective. You may use the course textbook, the lab manual and lectures as references. The references are included in a reference list at the end of the report. Decide what the main purpose of the lab is. Does it introduce a new method or does it demonstrate a reaction mechanism?

Pictures may be included, e.g. a drawing of some equipment, a schematic picture of a protein, a schematic overview of a biochemical pathway etc etc. Mathematical and chemical formula are also added to this section. Do not forget figure legends and numbering as well as references if you take pictures from the literature.

Common errors:
Some parts are left out.
Numbering of figures and/or figure legends are missing.

Methods
In this section you describe equipment, chemicals and how you did the experiment. If the work you are reporting is a computer tutorial you describe computer programs, data bases, and any particular data used (e.g. if you studied a protein structure identify it by its PDB ID code). In principle it should be possible to repeat the experiment without access to the lab manual. Describe in a concise way how the experiment was performed. Try to explain why things were done in a particular way, e.g. why a particular pH was chosen or why a particular chemical was added. Write this section the same day that you did the lab. Details are easily forgotten already the day after.

Common errors:
Wrong tense. The methods section should be written in imperfect i.e. past tense. Remember that the manual is written in imperative form i.e. it tells you how to do things. This means that you can't copy text directly from the manual.

Results
This is the most important part of the report where you should present the results you obtained as clearly and concisely as possible, e.g. absorbance measurements, colour changes, or observations of bands on a gel after electrophoresis. Raw data and calculated values may often be summarised in tables but do not forget to also describe the results in the text. Extensive presentations of raw data like long lists of absorbance measurements and calculations may be included in an appendix. References to figures and tables must be added both when they are present directly in the text as well in appendices. Do not forget to label axes in figures with both quantity and unit and that all tables must be numbered and have a clear heading.

Instructions for fitting data to a straight line
When you need to fit data to a straight line, use a least squares fitting procedure. This is available in e.g. Excel, many calculators also have in-built least squares fitting procedures. Use common sense to detect outliers and decide what data points to include. You may draw the line by hand if you do it carefully, but you must always include the equation for the least squares line and an estimate of the lack-of-fit to the line. Don’t forget to label the axes of your plot.

Common errors:
Raw data sometimes missing and only the conclusions presented.
Results not described in the text, tables missing or vice versa.
Legends, headings and references left out.
Calculated values contain too many decimals.
Samples/series not identified but simply presented as "sample 1, sample 2,..." or "series 1, series 2,...". You need to specify what the sample or series is.
Labels missing from plots.

Discussion
State again what the goal of the lab was. Discuss how these goals were accomplished and how your results compare to previous knowledge. Did you expect these results? Why? It is not correct to simply state that a result is "wrong" or "right". Instead you should make an effort to try to explain why you got a particular value or result.

Equipment that was used may be commented, maybe it is possible to develop or improve the method. Discuss possible errors. Are your results unambiguous or would it be possible to suggest additional experiments to exclude uncertainties?

Common errors:
You write e.g. "The experiment went very well and we got the results we had expected" i.e. the results are not compared to other facts.

The last two sections of the lab report may alternatively be combined into one section titled Results and discussion. The general outline should still follow the above mentioned recommendations.

Some of the labs include questions and discussion points. These are meant to point out things you should think about. Use them as support for your reports, in particular in the results and discussion sections. Do not simply answer them one by one.

References
Here you list the references you have given in your text. Each reference should list the author(s), year, title and page of the reference. You may either number the references as they follow in the text (1), (2) etc. Alternatively you indicate the name of the first author and publication year in the text e.g. (Smith et al., 1998). In the latter case the references are listed alphabetically.

Appendix
The appendix may contain documentation that is too extensive to be inserted inside the report, e.g. larger tables and calculations. Appendices should be numbered and referred to in the text.

Common errors:
No numbering or reference inside the report.

General
Leave your report in the lab report box marked "Bke1: Till lärare" in room 200 at GC. Lab reports must be handed in no later than 12:00 on the deadline day for the lab (deadlines are given in the schedule). Corrected and commented lab reports will be returned in the box marked "Bke1: Till studenter" approximately one week after the deadline for handing in reports, or at the lab follow-up for the lab. Each lab report that is handed in on time and that is passed without major revision will give a bonus for the final exam of 1% of the total exam points. Note that late reports will give no bonus and might not be corrected until after the course! No reports will be accepted after the final deadline (approximately two weeks after the end of the course).

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