Chapter 2.2 - Microscopes Flashcards
1
Q
What are the principles of light microscopes?
A
- Uses light to form an image
- Light that passes through or reflects from the surface of the specimen is seen
2
Q
What is the functionality of light microscopes?
A
- Magnification to 1500 x
- Resolution to 200nm
- Living and non-living specimens can be observed
- 2D colour images
3
Q
How do you use a light microscope? (5)
A
- Place the specimen on a slide which is fixed to a stage, and clip it in place, stain if needed
- Rotate the revolving nosepiece to the lowest power objective lens is over the specimen
- Adjust the coarse focus knob until the image is clear and in focus
- Adjust the iris diaphragm for optimum light
- Make sure the object is directly above the hole in the stage, rotate the nosepiece to the next greatest lens over the specimen. Look down the ocular tube and use the fine focus knob to focus the image
4
Q
What are the advantages of light microscopes?
A
- Small and relatively cheap
- Specimen preparation can be straightforward enough to perform in a school laboratory
- Produce colour images
- 2D
5
Q
What are the principles of transmission electron microscopes?
A
- Uses electrons to form an image
- Electrons that pass through the specimen are detected, creating contrast
6
Q
What is the functionality of transmission electron microscopes?
A
- Magnification to 500 000 x
- Resolution to 0.2nm
- Only dead or non-living specimens can be used
7
Q
What type of images so TEMs produce?
A
- High resolution
- Internal structures within cells and organelles can be seen
- 2D
8
Q
What are the principles of scanning electron microscopes?
A
- Uses electrons to form an image
- Electrons that are reflected from the surface on the specimen are detected
9
Q
What is the functionality of scanning electron microscopes?
A
- Magnification to 100 000 x
- Resolution to 10nm
- Only dead or non-living specimens can be used
10
Q
What type of images do SEMs produce?
A
- 3D
- Shows the surface of specimens
- Lower resolution than TEMs
11
Q
What are the principles of laser scanning confocal microscopes?
A
- Uses a laser bean to scan an object pixel by pixel, creating a 3D image of the reflected photons.
- 2D images of higher resolution can also be produced
12
Q
What is the functionality of laser scanning confocal microscopes?
A
- Requires a compromise between resolution, scan time, and photo destruction(laser can damage of the specimen
- Fluorescent dyes can be used to tag specific molecules
- Magnification to 18 000 x
- Resolution to 800nm
