Electron vs Light Microscope Flashcards
What can you see under a light microscope
It’s good enough to see cells, but not the detail of cell organelles
Can you see in colour with a light microscope
Yes, specimens can be seen in colour
Is there a wide field of view to observe the tissue structure under a light microscope?
Yes, a wide field of view of 2mm
Can you study moving specimens under a light or electron microscope?
Under a light microscope
Advantageous: the movements of the specimen can thus also be studied
Which has a greater resolution and magnification: a light microscope or an electron microscope?
An electron microscope
What is the approximate resolution of an electron microscope
0.1nm
What are the magnifications of an electron microscope
500,000
Instead of shining light through a specimen like a light microscope, what does an electron microscope do?
- The EM takes advantage of the short wavelength of the electrons.
- A beam of electrons is fired from a hot metal wire and focussed on the specimen by a series of electromagnets.
- Photographs are then produced (electron micrographs).
What do EM microscopes allow
The study of the organelles of cell structure
What two kinds of electron microscopes are there
Scanning Electron Microscope (SEM)
Transmission Electron Microscope (TEM)
How does a Scanning Electron Microscope (SEM) work
- we can see surface of 3D object in high resolution
- scans surface of object with focussed beam of electrons and detecting electrons that are reflected and knocked off the sample surface
How does a Transmission Electron Microscope (TEM) work
- shoots beam of electrons at thin surface of a sample
- detects electrons which make it out the other side
- useful for learning how components in the cell are structured
Disadvantages of electron microscopes
- specimens are dead due to the preparation technique (e.g. the staining, dehydration and placement in a vacuum)
- no movement can be studied as organism is dead
- field of view is very small
- expensive to buy (over $1,000,000)
- expensive to produce electron beams
- large and requires special beams
- lengthy and complex preparations
- preparation distorts material
- vacuum is required
- all images in black and white
Compare the magnification of a light microscope and an electron microscope
light microscope = magnifies only up to 2000 times
electron microscope = magnifies over 500,000 times
Advantages of a light microscope
- cheap to purchase ($100-$500)
- cheap to operate
- small and portable
- simple and easy preparations
- material rarely distorted by preparation
- vacuum not required
- natural colour maintained
What microscope is used to study cell organelles?
Both light and electron microscope
What microscope is used to study bacteria?
Both
What microscope is used to study proteins?
Only electron microscope
What does a light microscope have a resolution of
200nm
