Microscopy Flashcards
1
Q
Why is a thin layer of material used in histology?
A
- light transmission
- detail
- can also use cell culture
2
Q
Fixed samples
A
- opposed to live imaging
- main form is a chemical fixative formaldehyde
- can also use alcohol/acetone
- all designed to stop breakdown of sample and preserve sample
3
Q
Fluorescence (1)
A
fluorescent compound + absorbed light of right wavelength = light release t higher wavelength (less energy)
4
Q
Fluorescent imaging
A
- allows for successive tagging of specific structure/proteins in greater detail
- multiples probes used at same time
- done on fixed/live samples
- uses antibodies, dyes, and fluorescent proteins
5
Q
Fluorescence (2)
A
- electron excited from ground state by absorption of light
- fluorescence observed as electron decays = photon release
- energy lost = light emitted at longer wavelength
6
Q
GFP
A
Green Fluorescent Protein
7
Q
Phase contrast
A
- If the light from an object
to the edges of the objective lens is retarded a half wavelength and the light to the center is not retarded at all, then the light rays are out of phase by a half wavelength. They cancel each other when the objective lens brings the image into focus.
-A reduction in brightness of the object is observed. The degree of reduction in brightness depends on the refractive index of the object.
8
Q
Differential Interference Contrast (DIC)
A
Use of polarised to give similar effect
9
Q
How do we see fluorescence?
A
- dichroic mirrors and filter system
- Specialised filters to split colours
- Acousto optical crystals (AOTF/AOBS)
10
Q
Long/short pass filter
A
Transmits light above a cut-off point
11
Q
Band pass filters
A
Transmits light between 2 defined wavelengths
12
Q
Dichroic filters
A
Reflects lights up to one wavelength, and transmits beyond
