Lab 2: The Gram Stain: Identify and differentiate bacteria
Learning Outcomes
• Describe the structure of the Gram-positive and Gram-negative bacteria.
• Identify theoretical and technical aspects of the Gram staining procedure.
• Identify the most commonly made mistakes in Gram staining.
• Analyze the results of a Gram staining experiment using a light microscope.
About the Gram Stain: Identify and differentiate bacteria Virtual Simulation Lab
Did you know that there are approximately 5 million-trillion-trillion bacteria in the world? Most
of them are harmless, but some can induce disease in an affected host. In this simulation, you
will help doctors identify bacteria in a cerebrospinal fluid sample from a patient suspected of
suffering from bacterial meningitis.
Explore the bacterial cell wall
Compare and contrast the cell wall of Gram-positive and Gram-negative bacteria by building
your very own bacterial 3D models on the hologram table. Enter the exploration pod to observe
in an immersive animation how the four reagents of the Gram stain interact with structural
components of the cell wall to color the bacteria.
Perform the gram stain
When the patient’s fluid sample arrives at the laboratory, equip yourself with protective gear to
prepare a bacterial smear and heat fix it to a glass slide. You are now ready to perform the
Gram stain in a safe virtual environment. Made a mistake? No worries, hit the big red button on
the workbench to repeat the staining procedure until it becomes second nature.
Interpret your findings using a microscope
In the end, you will use a light microscope to interpret the results of your Gram stain. View the
microscopic image on the computer screen, and apply immersion oil to increase magnification
1000x! Will you be able to identify the presence of any bacteria in the patient´s cerebrospinal
fluid?
, BIOS242, Week 2-OL
Questions:
1. Purpose: Please describe in complete sentences and in your own words, the purpose of
this experiment.
The purpose of this experiment is to learn how to use the Gram stain method to identify
and differentiate between Gram-positive and Gram-negative bacteria based on their cell
wall structure. By understanding the differences in staining properties, we can identify
bacterial infections and help diagnose diseases, such as bacterial meningitis, in a patient
sample.