Topic 1: Development of practical skills ✿ Flashcards
How do light microscopes work?
The light is directed through the thin layer of the specimen on the slide, the light is focused through lenses so the image is visible through the eyepiece
How can you prevent dehydration of tissues under a microscope?
Adding water will prevent dehydration of tissue
How do you prepare a slide for a solid specimen?
Preparing a slide for a solid specimen:
1). Cut down the tissue so it’s small and thin
2). Place the thinned down specimen onto the slide and apply a stain
3). Place coverslip on gently, trying to prevent air bubbles
How do you prepare a slide for a liquid specimen?
Preparing a slide for a liquid specimen:
1).Add few drops of liquid specimen to slide using pipette
2). Gently place on coverslip
Why should the lowest power objective lens be used first?
The lowest power objective lens should be used first because it’s easier to find what you’re looking for in the field of view and prevents damage to the lens or cover slip if the stage is placed too high
Why should you do to the microscope if the image is unclear/blurry?
If the image is unclear/blurry, use the coarse focus to get a clear image, or make the specimen thinner, or get a new specimen as cross-contamination could of occurred
What are the limitations of the light microscope?
Limitations of the light microscope:
-The size of cells or structures of tissues may appear inconsistent in different specimen slides
-Optical microscopes do not have the same magnification power as other types of microscopes and so there are some structures that can not be seen
-The treatment of specimens when preparing slides could alter the structure of cells
Why should specimens be stained with a dye before being viewed under a microscope?
Specimens are stained with a dye because cells are naturally transparent, and dye therefore makes the cells visible. Specific dyes absorb specific colours of light, and certain tissues absorb certain dyes, depending on their chemical nature.
What is differential staining?
Differential staining is when specimens under a microscope are stained with various dyes to ensure the different tissues can be seen in the light
Why must specimens that are being viewed using an electron microscope must be stained?
When specimens are stained, they absorb the electrons. However, the dye on the staines do not show up as electrons have no colour
What are used as dyes when observing a specimen with an electron microscope?
Heavy-metal compounds are used as dyes when observing a specimen with an electron microscope because they absorb electrons well
With microscopes, what would increasing the magnification beyond the limit of resolution do?
Beyond the limit of resolution, increasing the magnification will increase the distance between the objects being measured
What type of microscope is an optical microscope?
An optical microscope is a transmission electron microscope
How do you calculate magnificiation?
Magnification = image divided by real size
What is the order that light passes through microscopes?
The order that light passes through microscopes:
Condenser > sample > objective lens > eyepiece lens
