Microscopy Flashcards
What is the equation for magnification?
Magnification = image size/ actual size
What is magnification?
- the degree to which the size of an image is larger than the object itself
- too high, can result in blurred image
What is resolution?
- the ability to see two distinct points separately that are very close together
- increases the level of detail
How do you calculate total magnification?
eyepiece x objective
What is staining?
Using chemicals that react with other chemicals in the sample to…
What is sectioning?
Using wax to stop the structure of the specimen from being distorted
Describe an electron microscope:
- uses beam of electrons with a wavelength of 0.004nm
- resolution = 0.1nm (500,000x greater than human eye)
- uses magnets to focus
- creates an electron micrograph
- allows us to image viruses and DNA, which are smaller than 200nm
What is an electron micrograph
an image on a screen or photographic paper created by an electron microscope
Describe optical microscopes
- magnification: x1500
- resolution: 200nm
- method: light beams pass via object
- image type: 2D
Describe SEM
- magnification = x100,000
- resolution = 1nm
- method: electron beam reflects off object’s surface; directed onto sample
- image type: 3D
Describe TEM
- magnification: x500,000
- resolution: 0.05nm
- method: electron beam passes through sample
- image type: 2D (the darker the parts seen, the thicker the sample)
Describe a TEM image
Slices through a plane of view which can be at any angle through any part of an organelle
Pros of an optical microscope:
- can see colour
- easy to use
- accessible
- relatively cheap
- do not need a vacuum; can observe a living sample
Cons of an optical microscope:
Low resolution and magnification; low retail
Pros of an electron microscope:
electrons have a smaller wavelength (up to 100,000x) therefore there is a higher magnification and higher resolution