BIOS 242 Week 3 Micro Gram Staining Lab

BIOS 242 Week 3 Micro Gram Staining Lab

Name

Chamberlain University

BIOS-242 Fundamentals of Microbiology

Prof. Name

Date

The Gram Stain: Identify and Differentiate Bacteria

Learning Outcomes

• Describe the structure of Gram-positive and Gram-negative bacteria.
• Identify the theoretical and technical aspects of the Gram staining procedure.
• Recognize the most common mistakes made during 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? While most of these bacteria are harmless, some can cause diseases in affected hosts. In this simulation, you will assist doctors in identifying bacteria in a cerebrospinal fluid sample from a patient suspected of having bacterial meningitis.

Explore the Bacterial Cell Wall

You will compare and contrast the cell walls of Gram-positive and Gram-negative bacteria by creating your own 3D bacterial models on a hologram table. Enter the exploration pod to observe an immersive animation that demonstrates how the four reagents of the Gram stain interact with the structural components of the cell wall to color the bacteria.

Perform the Gram Stain

When the patient’s fluid sample arrives at the laboratory, don 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. If you make a mistake, simply press the large red button on the workbench to repeat the staining procedure until you master it.

Interpret Your Findings Using a Microscope

Finally, 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 achieve a magnification of 1000x! Will you be able to identify the presence of any bacteria in the patient’s cerebrospinal fluid?

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 determine the Gram stain of the bacterial sample, which helps identify the chemical composition of the cell wall. The color of the stain will indicate whether the bacteria are Gram-positive or Gram-negative. Additionally, it can provide information about the shape, size, and arrangement of the cells.

2. Complete the following table by predicting colors of bacteria with and without cell walls as they are processed through the steps of Gram staining.

1. A fellow student showed you a Gram-stained slide where cells containing thick cell walls were stained pink. What would you tell her about the staining procedure? Why?
   A slide showing cells with thick cell walls stained pink indicates a Gram-positive bacterium. This suggests that an error occurred during the staining procedure, likely due to skipping the iodine step. The crystal violet would initially bind to the cells, but the subsequent addition of safranin would stain the bacteria pink.

2. A fellow student showed you a Gram-stained slide where cells containing LPS were stained purple. What would you tell her about the staining procedure? Why?
   A Gram-stained slide where cells containing LPS are stained purple indicates an error in the procedure. Gram-negative cells have LPS in their outer membrane, and if the decolorization step with alcohol was missed, the crystal violet and iodine would not be washed away, resulting in the Gram-negative bacteria appearing purple.

3. Reflection: Write five sentences on what you learned from this simulation. What did you like, and what would you prefer not to be a part of this simulation?
   In this lab simulation, I learned about the structural differences between Gram-positive and Gram-negative bacteria. I also discovered why they stain different colors based on their components, such as peptidoglycan and thick cell walls. Additionally, I learned the steps involved in performing a Gram stain and how to conduct the procedure myself. I was able to use a microscope to differentiate between Gram-positive and Gram-negative bacteria, along with their structure, size, and arrangement. I appreciated the simulation for its informative content and thoroughness, as it felt as realistic as possible.

Grading Rubric: Activity Deliverable Points

References

American Society for Quality. (2018). Quality Tools and Techniques.

Schwalbe, K. (2016). Information Technology Project Management.

EdrawSoft. (2018). Flowchart Software.

BIOS 242 Week 3 Micro Gram Staining Lab

Usmani, A. (2014). Statistical Analysis Tools.

Wilhite, R. (2017). Quality Management Principles.