Week_6A_L_BacteriaLab (See uploaded document and follow the instructions)

Unknown Eubacterium Shape Under Microscope Gram ) or (- ) G C Content ) rRNA Gene Sequence Matches With Type Strain

1 Cocci in cubical package 45 Sarcina sp

2 Curved rod with flagella - 37 Vibrio cholerae

3 Spiral with flagella - 70 Rhodospirillum rubrum

4 Straight rod - 51 Escherichia coli

5 Cocci irregularly arranged 25 Staphylococcus aureus

6 Cocci in chain 30 Streptococcus mutans

Bacterial Lab Compare traditional medical bacterial taxonomy to molecular taxonomy

The traditional medical bacterial taxonomy is based on morphological characters (shape , color and size of bacteria , colony morphology

habitat , staining ability , antibiotic sensitivity etc , but does not support evolutionary significances

Molecular taxonomy includes classification by determination of sequences of DNA , protein and RNA in the bacteria . This taxonomy does support evolutionary significances

Describe how a gram stain is used to identify bacteria . Can you determine a bacterial species using this method

Gram staining , introduced by Christian Gram (1884 , is a very popular method to determine the nature of bacteria . Here a stain named crystal violet is applied on bacteria (on slide ) followed by washing with alcohol or acetone then staining with a secondary stain . Microscopic observations reveal that some of the bacteria retain the violet stain and some shows the secondary stain only . Bacteria in the first instance are gram positive and other type is gram negative

This method is very useful in preliminary identification of bacterial type , but not sufficient for the confirmation or identification of bacterial species

How are guanine and cytosine DNA base...