Microscopes Flashcards
Magnification of light
X1500
Resolution of light
200nm
Magnification of laser scanning confocal
X2000
Resolution of laser scanning confocal
50nm
Magnification of transmission electron
X500,000
Resolution of transmission electron
0.2nm
Magnification of scanning electron
X100,000
Resolution of scanning electron
2nm
Difference between transmission and scanning electron
Transmission=better resolution
Scanning=3D
Why they have different resolutions
Different wavelengths.
Smaller wavelength=better resolution
Definition of magnification
How much an image has been enlarged by compared to the object
Definition of resolution
The minimum distance two points can be distinguished
Definition of staining
Using stains to create contrast between things and so they stand out against the background.
m->mm->um->nm
X1000
Magnification triangle
Image size
A sizeXmagnification
What are the advantages of using a light microscope?
They are the cheapest
Easy to use
Can be used for dead and living samples
Relatively easy to section/stain specimens
Why is it important to cut sections thinly when viewing under a microscope?
Light needs to be able to pass through the specimen
Clarity - you want to only be able to see a single layer of cells.
What 2 pieces of equipment are used to measure the actual length of an object under magnification?
Eyepiece graticule
Stage micrometer
What is differential staining?
Different parts of a cell/different cell types are stained with different things so they can be distinguished.
Some stains bind to specific structures within a cell so they can be easily picked out on a specimen.
What are light microscopes used to observe?
Whole cells and tissues
What are transmission electron microscopes used to observe?
Organelles
What are laser scanning confocal microscopes used to observe?
Cell surfaces
How do you measure the diameter of a structure on a microscope picture?
Use eyepiece graticule/stage micrometer
Align stage micrometer to eyepiece graticule
Calibrate length of each division of eyepiece graticule in um
Replace stage micrometer with slide and measure number of eyepiece divisions to determine size
What are the differences between optical and electron microscopes?
Optical uses light, can look at living samples, has a low resolution/magnification and can distinguish colour
Electron is opposite
What 2 stages are there to prepare a large tissue specimen for light microscopy?
Sectioning
Staining
Why do most specimens need to be stained?
Many cells are colourless so detail wouldn’t be seen
How do laser scanning confocal microscopes produce an image?
Specimen is dyed and lasers are used to cause fluorescence of the specimen
This allows depth selection through a thick specimen to construct a 3D model with high resolution
