Week 13 Flashcards
mention 4 points that show the importance of microscopy
1) advancements in scientific research
2) medical diagnostics and treatment
- histopathology
- blood cell analysis
- urine analysis
- semen analysis
3) material analysis and quality control
4) environmental and forensic analysis
3 main types of microscopes + new technological advancements
1) light microscopy
2) electron microscopy
3) scanning probe microscopy
- confocal microscopy (3D reconstruction)
- super-resolution microscopy (molecular level)
- correlative microscopy
3 types of optical microscopes
1) compound
2) stereo: 3D view
3) digital: images and videos
give 3 principles that explain how optical microscopes work
1) refraction and reflection of light
2) use of lenses and objectives to focus and magnify
3) principle of resolution (ability to distinguish between closely spaced objects)
What’s the difference between brightfield and phase contrast microscopy?
1) brightfield:
- light passes through the sample
- image is formed by the absorption of light by the sample
2) phase contrast
- exploits differences in refractive index of different parts of the specimen
- converts phase shifts into amplitude differences that can be visualized as variations in image brightness
How does darkfield work?
- specimen appears bright against a dark background
- sample is illuminated with oblique or off-axis light, so that only the light scattered by the specimen enters the objective lens.
for what is stereoscopy usually used?
To visualize big specimens or for material analysis
Give three types of electronic microscopes
- Transmission EM: beam of electrons goes through thin sample -> internal structures
- SEM: better for surface features (secondary + backscattered electrons, characteristic x-rays)
- reflection EM: surface composition and topography
What can be combined with SEM/TEM to analyse the chemical composition?
EDX (also called EDS)
what is one necessary sample preparation step for electron microscopy?
coating with a conducting material
give three examples of advanced microscopes
1) confocal: use a laser
2) AFM: measure forces between probe and surface -> surface topography/roughness
3) STM: images at atomic scale
What is a fluorochrome?
A fluorochrome is a molecule that absorbs light at one wavelength (the excitation wavelength) and emits light at a longer wavelength (the emission wavelength).
what is the importance of the pinhole in confocal microscopy?
By scanning a focused laser beam across the specimen and collecting emitted fluorescence through a pinhole, confocal microscopes selectively capture light from a specific focal plane while rejecting light from out-of-focus planes.
give 4 technological advancements in microscopy
1) digital imaging and analysis
2) fluorescence and confocal microscopy -> enhanced contrast and visualization of specific structures within specimens
3) super-resolution microscopy: surpass the diffraction limit -> ultrafine details
4) multi-dimensional imaging
applications in biological research (4)
1) microorganism observation
2) tissue imaging
3) live cell imaging
4) protein expression
