Cells (MICROSCOPES) Flashcards
What are the three types of microscopes
Light (optical) microscopes
Transmission Electron Microscopes (TEM)
Scanning Electron Microscope (SEM)
What are the 2 types of electron microscope
TEM and SEM
Which has a higher resolution, electron or light microscopes
Electron microscopes.
–> Light microscopes only have a resolution of 0.2 micrometres. Electron microscopes have a resolution about 1000 times higher than optical microscopes
Compare electron microscopes to light microscopes
Light microscope:
* Beam of light is condensed to create an image
* Lower resolution than electron microscope as light has a longer wavelength
* Lower magnification than electron microscopes
* Samples can be living
* Sample is show in colour
Electron microscope:
*Beam of electrons are condensed using an electromagnet to create an image
* Higher resolution than light microscope as electrons have a shorter wavelength
* Higher magnification than light microscope
* Staining process is more complex than light microscope
* Sample must be placed in a vacuum so cannot be living
* Sample is shown in black and white
Compare Transmission Electron Microscopes to Scanning Electron Microscopes
TEM:
*Beam of electrons need to pass through specimen so sample must be very thin
* Higher resolution than SEM
* Able to observe ultra cellular structure in great detail
* Produces a 2D image
SEM:
* Beam of electrons scan the surface of specimen so reflected beam is observed
* Lower resolution
* Can only see the surface
* Produces a 3D image
Which has a greater resolution TEM or SEM
TEM
Why are some parts of the specimen darker when viewed under a TEM
Some parts of the specimen (the denser parts) absorb the electrons making them appear darker.
Parts that are lighter allow electrons to pass through
What must you increase on a microscope to make the image less blurry
Magnification AND resolution
