Methods of studying cells Flashcards
What is magnification?
Increasing the size of the object being viewed.
What is resolution?
The ability to distinguish between 2 points.
Why is the wavelength of electrons better than for microscopes?
The short wavelength of electrons enables us to see an object in more detail - higher resolution.
Why is the wavelength of light worse for microscopes?
The long wavelength means a lower resolution.
Is a longer or shorter wavelength better for microscopes?
What type of microscope provides this?
Shorter
An electron microscope.
What is the resolution like for a light microscope?
A light microscope can only distinguish between 2 points if they’re 0.2μm or further apart.
What’s the resolution like for an electron microscope?
An electron microscope can distinguish between 2 objects at 0.1nm apart.
Equation for magnification:
image size / real size.
How does a light microscope work?
Specimens are illuminated with light.
Light is focused using glass lenses and viewed using an eye piece.
Specimen need to be stained with coloured dye to make them visible.
What type of specimens can be viewed using a light microscope?
Living or dead.
How does a transmission electron microscope work?
A TEM uses electromagnets to focus an electron beam.
The beam is transmitted through the specimen, specimen must be thin.
Denser parts of the specimen absorb more electrons to appear denser.
What is a benefit of TEMs?
They give higher resolution images.
What type of image does a TEM produce?
A 2D image.
What type of specimen can be looked at in the TEM vacuum?
The specimen cannot be living.
How does a scanning electron microscope work?
An electron beam is scanned across the specimen.
This displaces (knocks off) electrons from a specimens surface.
Electrons are collected in a cathode ray tube and form an image.
