Studying Cells Flashcards
(33 cards)
What are the three types of microscopes?
Scanning electron microscope
Transmission electron microscope
Optical microscope
Define magnification.
How many times larger the image is compared to the object.
Define resolution.
The minimum distance between two objects in which they can still be viewed as separate.
What is resolution determined by in an optical microscope?
Wavelength of light - longer wavelength of light makes resolution poor in optical microscopes.
What is resolution determined by in an electron microscope?
Wavelength of beam of electrons - shorter wavelength of electrons makes resolving power higher in electron microscopes.
Compare how images are created in optical microscopes and electron microscopes.
OM - Beam of light is condensed to create the image.
EM - Beam of electrons are condensed to create the image. Electromagnets are used to condense the beam.
Compare resolution in optical microscopes and electron microscopes.
OM - poor resolution due to longer wavelengths of light.
EM - higher resolving power due to shorter wavelength of electrons.
Compare magnification in optical microscopes and electron microscopes.
OM - lower magnification
EM - higher magnification
Compare image colour in optical microscopes and electron microscopes.
OM - colour images can be produced.
EM - black & white images produced.
Compare if the specimen are dead or alive in optical microscopes and electron microscopes.
OM - living samples can be viewed.
EM - only dead samples can be viewed.
Why can only dead samples be viewed in electron microscopes?
Electrons are absorbed by air which is why samples must be in a vacuum and thus only dead samples can be viewed.
Why can only black and white images be produced in electron microscopes?
The samples must be stained.
Why can’t we see smaller organelles in optical microscope?
Longer wavelength of light.
How does the Transmission Electron Microscope work?
Extremely thin specimens are stained and placed in a vacuum.
An electron gun produces a beam of electrons that pass through the specimen.
Why are some parts of the image created by TEM darker?
Those parts absorbed electrons.
What kind of image is produced from the TEM?
2D and detailed.
What is different between the SEM?
The specimen doesn’t need to be thin.
Why does the specimen not need to be thin for the SEM?
Electrons aren’t transmitting through.
What happens during SEM?
Electrons are beamed onto the surface and the electrons are scattered in different ways.
How are the electrons scattered into different ways in SEM?
The different depths of the specimen would affect the scattering of the electrons.
What type of image is produced?
3D
Magnification equation?
I = AM
What is image size measured in?
Millimeters.
What is actual size measured in?
Micrometers.
