What is magnification in microscopy?
The ratio between observed dimension and actual object size.
What does the resolution limit define in microscopy?
The minimum distance to distinguish two objects.
What factors determine the resolution limit in microscopy?
Light diffraction, numerical aperture, and refractive index.
What type of light does visible transmitted light microscopy use?
Polychromatic light in air.
What type of light does fluorescence microscopy use?
A single monochromatic wavelength.
What is the resolution limit in visible light microscopy?
200 nanometers.
What does confocal fluorescence microscopy do to the resolution limit?
It decreases the resolution limit.
How does confocal fluorescence microscopy handle samples for imaging?
It divides samples into thin slices.
What can be created by recombining thin slices in confocal fluorescence microscopy?
A three-dimensional image.
What particles does photon microscopy detect?
Photons.
What is the resolution limit of photon microscopy?
200 nanometers.
What is the resolution limit of electron microscopy?
0.3 nanometer or less.
What does transmission electron microscopy (TEM) detect to form an image?
Electrons passing through non-opacified regions of the sample.
What are the main steps in TEM preparation for viewing subcellular structures?
Fixation, dehydration, resin embedding, thin sectioning, and opacification.
Why is resin embedding required for biological samples in TEM?
Because biological samples do not resist vacuum and are relatively transparent to electrons.
Why is opacification with heavy ions necessary in TEM?
To increase electron contrast by making regions less transparent to electrons.
Which chemicals can be used for TEM opacification?
Osmium tetroxide or immunogold.
What is the purpose of immunogold in TEM?
To localize a protein of interest.
What does scanning electron microscopy use to excite and detect samples?
A mobile beam progressively excites and detects the sample.
What preparation techniques does SEM use to produce a replica?
Cryofracture, surface sublimation, and shadowing with heavy ions.
Which heavy ions are used in SEM shadowing?
Platinum or silver ions.
What three-dimensional structures can SEM reveal after freezing and shadowing?
Cells or macromolecules.
Test your knowledge with 14 questions on Cell Biology Microscopy Techniques.
1. What does magnification measure in microscopy?
2. A microscope can produce a very large image, but two nearby points still appear as one blurred point. Which property is limiting the observation?
Review the complete course in the study sheet for Cell Biology Microscopy Techniques.
See study sheet →Import your course and AI generates flashcards in 30 seconds.
Flashcard generator