06 Dec “Lab 3 Structure & Microscopy BIO250L” Student Name: Click here to enter text.

“Lab 3 Structure & Microscopy BIO250L”

Student Name: Click here to enter text.

Access Code (located on the underside of the lid of your lab kit): Click here to enter text.

 

“Pre-Lab Questions”

1. What determines if a bacterial cell is Gram-positive or Gram-negative? Click here to enter text.

2. In this lab, both viruses and prions were introduced as acellular organisms. Do some research and describe one other type of acellular organism. What characteristics about this organism classify it as acellular? Click here to enter text.

3. Bacteria have many different shapes that often determine their class. Research and form a hypothesis on the evolutionary reasons for so many different bacterial morphologies.

4. Do a search online or look in your textbook for 1-2 antibiotics that affect Gram-positive bacteria and list them. On what part of the cell do the antibiotics usually work? List one or two antibiotics that affect Gram-negative bacteria? On what part of the cell do the antibiotics usually work? (Be sure to cite your sources in your answer.) Click here to enter text.

5. Why do you think it is important to identify a bacterial disease in a patient before prescribing any antibiotic treatments? (Be specific.) Click here to enter text.

“EXPERIMENT 1: Staining

Data Tables

Table 1: Experiment 1 Staining Observations

Stain Used:	Click here to enter text.
Observations:	Click here to enter text.

 

 

Post-Lab Questions

1. How does crystal violet enhance the visualization of microbial features? Click here to enter text.

2. What are some of the limitations of simple staining? Click here to enter text.

3. Give an example of a situation in a lab or medical setting in which simple staining would be utilized. Click here to enter text.

Insert a photo of your stain. Include your name and access code handwritten in the background of your photo.

 

 

“EXPERIMENT 2: Negative Staining

Data Tables Table 2: Experiment 2 Staining Observations

Stain Used:	Click here to enter text.
Observations:	Click here to enter text.

 

Post-Lab Questions

1. After visualizing the stained samples either using your microscope or by looking at the sample images provided, describe what physical/visual characteristics you were able to observe after performing the negative staining vs. after performing the simple stain. Click here to enter text.

2. So far in this lab, you have used one type of simple stain and one type of negative stain, yet there are many other simple and negative dyes available. Pick one simple dye and one negative dye, and discuss how those dyes differ from the ones you used in this lab. Give a scenario in which their use would be appropriate. Click here to enter text.

Insert a photo of your stain. Include your name and access code handwritten in the background of your photo.

 

 

EXPERIMENT 3: Gram Staining

Data Tables

Table 3: Experiment 3 Staining Observations

Stain Used:	Click here to enter text.
Observations:	Click here to enter text.

 

Post-Lab Questions

1. What color are the Gram-positive bacteria after Gram staining? Gram-negative bacteria? Click here to enter text.

2. What different characteristic(s) exist between the two groups that account for the different staining conditions? Click here to enter text.

3. Why was the Gram iodine added to the Gram staining procedure? Click here to enter text.

4. Why is a counterstain (safranin) added to the Gram staining procedure? Click here to enter text.

5. What are the advantages of performing a Gram stain vs. a simple stain for visualizing bacteria? Click here to enter text.

6. Using either a textbook or a reputable online resource, research some of the typical characteristics of bacteria, and discuss why it might be important for a researcher or a hospital technician to be able to differentiate between Gram-positive and Gram-negative bacteria. Click here to enter text.

7. Did you experience any technical difficulties or atypical results during this experiment? If so, what happened, and how could you avoid these issues in the future? Click here to enter text.

 

Insert a photo of your stain. Include your name and access code handwritten in the background of your photo.