Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet.
Submissions without proper
... [Show More] formatting, all required photos or sufficient responses will be rejected.
Pre-lab Questions
1. In this lab, you will conduct three experiments. What is the ultimate goal of those experiments
in the context of this lab? What learning outcomes do you think this lab is attempting to convey
with them?
This lab experiment teaches us basic microbiological techniques and microscopy, including
simple staining, negative staining, and Gram staining. It focuses on observing and identifying
bacteria's shape and arrangement, demonstrating the differences between simple and negative
staining, and distinguishing between Gram-positive and Gram-negative bacteria. The lab
emphasizes the clinical relevance of staining techniques, such as Gram staining, in medical labs.
Students develop practical laboratory skills, including preparing bacterial smears and using a
microscope.
2. Explain the purpose of staining in the context of microbiology. Why do we utilize various
staining techniques?
In microbiology, staining is used to increase the contrast between the microorganism and the
background, making it easier to observe under a microscope. Various staining techniques are
used to distinguish different types of microorganisms, their structures, and their presence in a
sample.
3. Each experiment in this lab will cover a different staining technique. List those techniques below
and provide a brief explanation of when each of those techniques would be used.
○ Gram staining is one of the most common staining techniques in microbiology. It is used
to classify bacteria into two groups: gram-positive and gram-negative. The difference is
due to the bacteria's cell wall composition, which influences stain uptake.
○ Negative staining is used to visualize cells or structures that are resistant to traditional
staining techniques. The stain colors the background while leaving the cells or structures
uncolored.
○ Simple staining: A single stain is used to color all cells the same color, with no
differentiation of cell types or structures.It is used to determine the morphology and
“Lab 3 Structure & Microscopy BIO250L”
arrangement of bacterial species.
“Lab 3 Structure & Microscopy BIO250L”
EXPERIMENT 1: SIMPLE STAINING
Introductory Questions
1. What is the objective of Experiment 1?
To calculate the proportion of cells in each stage of the cell cycle.
2. What is the purpose of Step 8 under Smear the Slide in this experiment?
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.
Simple staining can be used to quickly and easily determine the shape, size, and arrangement of
bacteria cells. Methylene blue, safranin, or crystal violet are some of the dyes used to stain
bacterial cells. [Show Less]