Stains Dichotomous Key
Classification is often done through use of a dichotomous key, a series of binary decisions (yes/no, true/false, blue/green, rod/circle, etc) based on features of what is being classified, whether it is bacteria or candy. The attached files show two ways that a dichotomous key can be constructed for classification of candy. In both forms, the largest distinction is placed at the top and is followed by further distinctions until all items are classified. The flow chart version is often easier to understand so start with that. The tabular format at first is more difficult to understand but works the same way except that instead of lines connecting from higher to lower keys, a series of jumps (go to’s) are used.
For this assignment you will need to produce a dichotomous key for the following organisms
Bacillus megaterium
Corynebacterium hofmanni
Klebsiella pneumonia
Micrococcus luteus
Mycobacterium smegmatis
Proteus vulgaris
Rhodospirillum rubrum
Spirillum serpens
Staphylococcus auerus
based on their morphology and staining (use any or all of the stains used/observed in lab – simple, gram, acid-fast, spore, flagella and capsule). To construct your dichotomous key, begin by creating a table listing the organsims across the columns and their morphology and staining down the rows. Once constructed, find the row that provides the most complete division into two groups (hint: it will be what can be considered THE microbiology stain). Then move rows to sort by increasing refinement. Your first row will be the first pair in the tabular construction or the first box in the flow chart. Since the flow chart is easier to visualize, you may find it useful create it in its entirety to check your key then convert to tabular format. If you can generate the flowchart in digital form, it can be submitted instead.
Use the attached Word document ( DichotomousKey.docx ) for creating your tabular submission, or use the PowerPoint document ( DichotomousFlowChart.pptx ) if doing a flow chart. You can also manually draw the flow chart. For security, append your student ID to the filename when you submit it.
