Reminders for biology papers

Writing papers in the biological sciences is very different from writing papers in English classes.  Here are some things to remember for science papers or lab reports.

Guidelines for “Materials and Methods” Section

The Materials and Methods (M&M) section is a technically detailed description of the materials and equipment used and the conditions under which your experiments were carried out.  The M&M is a resource for readers who want to repeat your experiments or apply your methods to their own systems, or who may be doing similar work and want to know whether their own experimental conditions are comparable.  This section is not where the reader looks to find out the overall story of the experiments you are reporting; in fact, many readers skip this section unless they are looking for a particular technical detail.  This section is very specific, dry, and terse, giving only enough information to define the conditions critical to the experiment.

1.  Write in past tense, using passive voice (yes, passive voice is okay here!).

2.  You can divide the M&M section into subsections, each with a subtitle, describing various techniques that were used.  The subsections do not need to be arranged chronologically – if you perform a task three different times, one description should suffice.  Also, if you find yourself repeating the same statement several times, you may choose instead to make a blanket statement at the beginning, before the subsections.

3.  Try to define the experimental conditions without necessarily giving a play-by-play narrative of each step.  For example, you can define the overall assay conditions by stating the reaction volume and reagent concentrations, temperature, and the means by which reaction was monitored.  Avoid excessive detail about steps that do not affect the outcome (i.e. “the sample was transferred into a beaker”; “the volume was measured”; “a sample was saved”) – many of these things are assumed, and these kinds of statements make it difficult for the reader to find the important information. 

4.  It is most important to report the final concentrations of reagents in the experimental samples – what concentration stock you used and how you diluted it are a matter of personal choice, and someone else may choose another approach and still achieve the same final conditions.  (If, however, you believe that some aspect of how you prepared or diluted a reagent is critical to the outcome of the experiment, you should include the pertinent information.)  This goes for dilutions of enzyme fractions as well, although a statement that fractions were sometimes diluted is important.

5.  Give sources for any specialized equipment, reagents, or products.  If you don’t know where you got an enzyme or buffer, ask your professor.

Guidelines for “Results” Section

The Results section tells the actual “story” of what you did and what you observed as you did it.  The M&M section is written in a terse, dry form and gives technical details.  The Results section is where you explain what you set out to do and how the observations along the way motivated each subsequent experiment.  Note also that the M&M section often appears in small print at the end of a journal article; i.e., you should not assume the reader has looked at M&M before reading the Results section.

Step 1:  Assemble figures and tables

To write your Results section, first gather all your data and make sure all your calculations are complete and done correctly.  Then decide on a form in which to present your data – some data are visual (gels), while others are best presented in tabular form (e.g. purification tables) and others are best appreciated graphically (e.g. column elution profiles).  You do not need to include your raw data; the reader trusts you to have treated your data appropriately.  Arrange the figures/tables in a logical order.

A note about data:  Many students tend to include way too many significant figures when reporting data.  Just because your calculator or spreadsheet spits these out doesn't mean it's valid to include all of them.  In general, 3 significant figures is sufficient, but check with your professor.

Step 2:  Write text to accompany the figures and tables

This step is a little bit like writing a story by drawing the illustrations first, then writing a narrative to say what’s going on in the pictures.  It may help to pretend that you are giving an oral presentation on your work.  What slides would you show and what would you say as you showed them, so that the audience understands what you were trying to do or ask, how you went about doing it (though without the boring technical detail), what the results were, and what they mean?

A note on What Results Mean:  Some professors prefer that you discuss only results in the Results section, and leave all discussion about what they mean to the Discussion section.  Ask your professor how s/he feels about that.  But things like WHY a given step was effective or not, how a step might have been made more effective, and how the results might either relate to what’s already known about this field should be left for the Discussion.

A note on journal articles:  Although figures and tables appear interspersed with text in a printed journal article, they are appended separately at the end of the text in a manuscript.  Each figure or table should have a legend describing what is depicted.  (You can put the legend with each figure separately, or you can have a separate page with all the figure legends – the latter is the way it’s actually done for a manuscript submitted to a journal.)   Remember to double space your text just as you do in the body of the paper.

How to cite references in scientific papers (i.e., not how you learned in ENG 104)

There are two basic styles of citation in scientific papers.  They differ both in the way the reference appears in the text as well as in the order in which the references are listed in the References section (which follows immediately after the Discussion section, preceding the Figures and Tables).

Method A

In text, list author(s) and year of publication, e.g (Levin, 1999).  If there are two

authors, list both, e.g. (Levin & Ungar, 1999).  If there are more than two authors,

use “et al.”, e.g. (Levin et al., 1999).

In the references section, list the citations in alphabetical order by first authors’ last names.  Include all authors here.  Typically, paragraphs are “reverse” indented; i.e., the first line starts at the left margin, and subsequent lines are indented.  There are many possible formats (varying by journal), but a common one lists authors, then year, then title, then journal name, volume number, and page numbers.  Example:

Levin, J. R., Ungar, S. J., and Clinton, H. R.  (1999)  The biochemical basis for

feminine dominance in marital relationships.  Journal of Irreproducible

Results, 135, 493 – 499.

Method B

In text, give each reference a number in the order that it appears in the text, i.e., the first paper cited is given number 1, the next is number 2, etc.  The numbers increase continuously through the whole manuscript; if you have 6 citations in the Intro, your first citation in the M&M is number 7.  If you refer to a source to more than once, use the number that you gave it the first time you cited it.  The numbers usually go in parentheses at the end of the sentence in which you reference the statement, although some journals use superscripts instead of parentheses.  Example:

This is a statement of scientific fact that needs to reference a previously published article (1).  This is another study that also provided evidence for the argument I am trying to make (2).  The first paper, as well as another one I haven’t mentioned before, also makes another point that I think is important to mention (1, 3).

For this method, list the references in numerical order rather than alphabetical order in the References section.  Example:

1.  Levin, J. R., Ungar, S. J., and Clinton, H. R.  (1999)  The biochemical basis for feminine

    dominance in marital relationships.  Journal of Irreproducible Results, 135, 493 – 499

2.  Abbott, T. K., and Costello, G. W. (1948)  Who’s on first?  Journal of American  Comedy,

    83, 106 – 128.

3.  Lennon, J., McCartney, P., Harrison, G. and Starr, R.  (1965)  How to succeed in the musical

     entertainment industry.  Journal of Rock and Roll, 12, 3476 – 3482.

Acknowledgments:

Dr. Judith Levin

Contact Judy Levin c/o:

Goucher College

Hoffberger Hall – Departments of Biology and Chemistry

1021 Dulaney Valley Road

Baltimore, MD 21204