Microscopy Flashcards
What is a light microscope used for?
Observing living and dead specimens.
What are the pros and cons of a light microscope?
Pros: Cheap, portable, easy to use, can study living specimens. Cons: Limited magnification, poor resolution.
What is a laser scanning confocal microscope used for?
Creating a high resolution, high contrast image, at different depths of the specimen.
What is a transmission electron microscope used for?
Observing the internal ultrastructure of cells under high magnification and resolution.
What is a scanning electron microscope used for?
Viewing the surface of objects under high magnification and resolution.
What are the pros and cons of an electron microscope?
Pros: Very high magnification and excellent resolution. Cons: Specimen has to be dead, very expensive, very large, needs great skill and training to use.
What is the difference between a transmission and a scanning electron microscope?
TEM sends a beam of electrons through the specimen, the SEM bounces electrons off the surface.
What is the difference between light and electron microscopes?
Light uses lenses to focus a beam of light. Electron uses a beam of electrons, focused by magnets.
What is an eye piece graticule?
A small ruler fitted to a light microscope’s eyepiece. It must be calibrated using a stage micrometer before being used to measure specimens.
What is a stage micrometer?
A millimeter long ruler etched onto a slide. It has 100 divisions, each of 0.01mm or 10 micrometers. It is used to calibrate the eyepiece graticule.
Why do we stain specimens?
To provide more contrast, and make it easier to distinguish certain parts.
What is differential staining?
Using a stain to distinguish between either 2 different organisms, or between organelles of a specimen due to preferential absorption of stain.
What is the formula to calculate magnification?
Magnification = Image size / Actual size.
What is the formula to calculate actual object size?
Actual size = Image size / Magnification.
How do we work out image size?
Use a ruler and measure the image.
What is magnification?
A measure of how much larger the image of a specimen looks under the microscope.
What is resolution?
The ability to distinguish between two adjacent individual points as separate.
What are the maximum resolutions of the different microscopes?
Light: 200nm; SEM: 10nm; TEM: 0.2nm.
What is the maximum magnification of the different microscopes?
Light: 1,500X; SEM: 100,000X; TEM: 500,000X.
