Microscopes - 2 Flashcards
What does magnification mean?
The degree to which the size of an image is larger than itself
What is the resolution
The ability to distinguish between two points
What are the three types of microscopes
Light
Laser scanning
Electron
How does a laser scanning microscope work
Uses a laser to scan an object
Image is displayed on computer screen
Advantages of a laser scanning microscope
High resolution and high contrast
Can focus at different depths
Multiple images can be combined to make a 3d image
What are the two types of electron microscopes
Transmission electron microscope
Scanning electron microscope
State 3 differences between TEM and SEM
TEM - electrons pass through specimen, SEM - electrons bounce off specimen
TEM image is 2D, SEM image is 3d
TEM has a higher magnification
What is the resolution of a light microscope
200nm
What is the resolution of an electron microscope
0.1nm
What is sectioning
Thin sections of a specimen are cut so light can easily pass through it
What is staining
Stains are used which bind to chemicals or structures in or on cells
This colours the specimen enabling it to be seen
What is differential staining
Some stains bind to specific structures meaning these can be
differentiated from others
Name two stains
Methylene blue
DNA red
