Total PURPOSE The Purrose of Gram Staining is for identifying and Clasifying Gram stain enables gram Positive or gram negative bacteria for example to Clasify bacteria as either EXPECTED RESULTS Bacterium Color Gram Staining red 1 What color will a gram negative cell stain 2 What color will a grand positive cell stain Rurple 3 Which organism used in this exercise is a coccus Sta Phylococus epidermis magnification Morphology and arrangement RESULTS Sketch a few bacteria viewed with the oil immersion objective lens gram negative Staphylococcus epidermidis DE 1000 x Cocci red red Bacillus subtilis Ce gram Positive Escherichia coli 1000x bacili Purple 2 Did your results agree with the information in your text QUESTIONS 1 Why do gram positive cells more than 24 hours old stain gram negative 2 Can iodine be added before the primary stain in a Gram stain 3 List the steps of the Gram ataining procedure in order omit washings and fill in the color of gram positive cells and gram negative cells after each step Step 1 2 3 4 Chemical Gram Positive Cells Appearance Gram Negative Cells 4 Which step can you omit without affecting determination of the Gram reaction CRITICAL THINKING 1 Suppose you performed a Gram stain on a sample from a pure culture of bacteria and observed a field of red and purple cocci Adjacent cells were not always the same color What would you conclude 2 Suppose you are viewing a Gram stained field of red rods and purple cocci through the microscope What do you conclude