Lab 1: Microscopy Flashcards
What is a common characteristic of all microbes?
Their small size
Most microorganisms require a microscope for visualization.
What types of microscopes will be used in the lab?
Bright-field and phase-contrast microscopes
How does bright-field microscopy work?
Light passes through the specimen
It is good for visualizing colored specimens and stained bacteria.
What is a limitation of bright-field microscopy?
Live bacteria are transparent and difficult to visualize
This makes observing live specimens challenging.
What is the advantage of phase-contrast microscopy?
Allows observation of living organisms in fluid samples
It exploits differences in refractive indices to create contrast.
What are the magnifications provided by ocular lenses and objectives?
Ocular lenses provide 10X magnification with final magnifications of 100X, 400X, and 1000X
The objectives include 10X, 40X, and 100X.
What should you use to clean the 100X objective after use?
Lens paper
Avoid using Kimwipes, Kleenex, or paper towels.
What is the purpose of using immersion oil with the 100X objective?
Minimizes refraction of light
The immersion oil has a similar index of refraction as the coverslip glass.
What is the role of micropipettes in microbiology?
Used for accurate measurement of small volumes
They help keep cultures pure and free of contaminants.
What is a Winogradsky column?
A culture of mud and pond water
It provides a large diversity of microorganisms at different gradients.
What changes occur in hay and pasture infusions over time?
Initially, bacteria predominate; unicellular eukaryotic protozoa become evident after several weeks
Populations vary and may congregate at different gradients.
Define true motility.
Purposeful and self-propelled movement
It is independent of the suspension and may involve changes in direction.
What are the two types of appendages used for movement by protozoa?
Flagella and cilia
Flagellates use flagella; ciliates like paramecium use cilia.
What is Brownian motion?
Random motion of particles due to bombardment by molecules
It is not considered true motility.
What is silage?
Fermented plant material used to preserve food
It is produced from grasses and other green forage crops.
What are the steps to prepare silage?
- Combine chopped forage with salt
- Pack into a container
- Ensure material is submerged
- Incubate at room temperature
Lactic acid bacteria will catalyze the fermentation.
What is the purpose of adding salt to the chopped forage in silage preparation?
To help release water from the vegetable material
This facilitates fermentation.
