1 Lab Microbio Quiz Prep

What is the purpose of preparing a bacterial smear?

To attach bacteria to a microscope slide so they can be stained and observed.

 Q: What are the 3 main goals of making a good smear?

• Adhere cells to the slide

• Prevent cell shrinkage/distortion

• Make the smear thin enough to see individual cells

Why should a bacterial smear be thin?

 So individual cells, their shape, arrangement, and structures can be seen clearly.

What happens if a smear is too thick?

Cells clump together, structures/arrangements are difficult to see, and stain can become trapped and give incorrect staining results.

How does preparing bacteria from broth differ from preparing bacteria from solid media?

 Broth: bacteria can be placed directly onto the slide.
Solid media: put water on the slide first, then mix a very small amount of bacteria into it.

What must happen before heat fixation?

The smear must completely air-dry.