Visualizing Proteins, Lipids, and Cells Flashcards
Lecture 7
What are the 3 challenges of visualization?
Magnification
Resolution
Contrast
What are the two kinds of microscopy?
Light and electron microscopy
What are the 5 kinds of light microscopy?
- Brightfield
- Phase-Contrast
- Differential Interference
Contrast (aka. Nomarski) - Darkfield
- Fluorescence
What are the 3 kinds of electron microscopy?
- Scanning (SEM)
- Atomic Force (AFM)
- Transmission (TEM); CryoEM
What is resolution?
ability to distinguish two closely positioned objects
Which has better resolution, shorter or longer wavelengths?
shorter
What is the refractive index (n)?
measure of the medium’s ability to bend light
Which has better resolution, a lower or higher refractive index?
higher
What does sin(theta) notate?
angle of the light captured by the objective
What is the numerical aperture?
refractive index * sin(theta)
ability of objective to capture light
What is Abbé’s limit of resolution?
after calculating resolution, 2+ things that are closer together than that value cannot be distinguished from each other
What is the wavelength of an electron inversely proportional to?
accelerating voltage
What do electrons move through in an electron microscope?
Vacuum; cannot move through glass well
How do electron microscopes work?
Electrons are moved via voltage through a vacuum onto a sample.
What focuses the electron beam, rather than glass lenses?
magnetic lenses
