Module 2: Microscopy. Flashcards
(44 cards)
What is the formula for magnification?
Magnification = image size / real size.
millimeter to micrometer?
x1000
micrometer to nanometer?
x1000
Micrometer to millimeter?
divide by 1000.
Nanometer to micrometer?
Divide by 1000.
Define Magnification.
How much bigger the image is than the actual specimen.
Define Resolution.
How detailed the image is.
How well a microscope distinguishes between 2 points that are close together.
(the smaller the number the higher the resolving power)
What is the Maximum Magnification for Compound light microscope?
x1500
What is the Maximum Resolution for compound light microscope?
0.2 micrometers (200nm)
Describe the compound Light Microscope.
A light source shines through the specimen. (This is often below the specimen).
The objective lens produces a magnified image that is then magnified again by the eyepiece.
Resolution is limited by by the wavelength of light and diffraction of light as it passes through the sample.
The images tend to have low contrast as most cells do not absorb a lot of light. This is why cells are often stained to increase contrast.
What are the advantages of Compound Light Microscope?
It is inexpensive.
It is portable and it does not require a lot of time to prepare.
Specimens can be living or dead.
What are disadvantages of Compound Light Microscope?
It has a low magnification and resolution compared to the Electron microscope.
Internal structures cannot be viewed.
What is the Maximum Magnification for Laser Scanning Confocal Microscope?
x2000
What is the maximum Resolution for Laser Scanning confocal Microscope?
0.2 micrometers (200nm)
Describe Laser Scanning Confocal Microscope.
A laser beam is focused through a lens which is aimed at a beam splitter. This splits the beam and some of the light is directed to the specimen.
When the laser hits the dyes it causes them to give off fluorescent light. This light is then focused through a pinhole onto a detector.
The detector is hooked up to a computer, which generates an image. The Pinhole means that any out of focus light is blocked.
Very thin sections can be examined and a high resolution can be produced.
A 3D image can be produced by creating images at different focal planes.
What are the Advantages of Laser Scanning Confocal Microscope?
Simple sample Preparation.
Specimens can be living or Dead.
What are the disadvantages of laser Scanning Confocal Microscope?
Expensive to buy.
Has a low magnification and resolution compared to the electron Microscope.
What is the Maximum Magnification for TEM?
magnification over x100 000
What is the Maximum Resolution for TEM?
0.0005 micrometers (0.5nm)
Describe Transmission Electron Microscope.
TEM’s uses electromagnets to focus a beam of electrons, which is then transmitted through a specimen to produce 3D images.
Denser parts of the specimen absorb more electrons, which makes them look darker on the image you end up with.
The specimen is kept in a vacuum to ensure the electron beams travel in a straight line.
What are the Advantages of TEM?
It has a high resolution and magnification.
Can view internal structures.
Need to be thinly sliced. The angle at which specimens are cute can affect how they appear.
What are the disadvantages of TEM?
Expensive to buy and operate.
Large and needs to be installed.
Time consuming.
Complex sample preparation.
Risk of artefacts.
Specimens are dead.
Black and white images are produced.
What is the Maximum Magnification for SEM?
Magnification over x500 000
What is the Maximum resolution for SEM?
0.002 micrometers (2nm)
