M2: Microscopes & Staining Flashcards
2.1.0 Foundations in Biology:
What’s Magnification?
I = AM
How much bigger an image is than the actual object
2.1.0 Foundations in Biology:
What’s meant by Resolution?
Distance between 2 points so they can’t be seen as one
2.1.0 Foundations in Biology: Light Microscope
What’s a Light Microscope?
Beam of light focused w lenses to produce an image
2.1.0 Foundations in Biology: Light Microscope
What are the Advantages of using a Light Microscope?
- Easy to use
- Cheaper
- Studies living organisms
- Coloured image
2.1.0 Foundations in Biology: Light Microscope
What are the Disadvantages of using a Light Microscope?
- 200nm resolution
↳ long wavelength of light - x1500 max mag
2.1.0 Foundations in Biology: Laser Microscope
What’s a Laser Microscope?
Scans object point by point & computer assembles it into an image
2.1.0 Foundations in Biology: Laser Microscope
What are the Advantages of using a Laser Microscope?
- Studies living organisms
- Has depth selectivity
↳ focuses on structures at diff depths
2.1.0 Foundations in Biology: Laser Microscope
What are the Disadvantages of using a Laser Microscope?
- More expensive
2.1.0 Foundations in Biology: TEM
What’s a TEM?
(Transmittion Electron Microscope)
Electromagnets used to focus beam of electrons through specimen
2.1.0 Foundations in Biology: TEM
What are the Advantages of using a TEM?
- 0.1nm max resolution
- x5,000,000 max mag
- Not alive
↳ used for internal structures - 2D
2.1.0 Foundations in Biology: TEM
What are the Disadvantages of using a TEM?
- Expensive
- Training needed to use
- Black & White image
2.1.0 Foundations in Biology: SEM
What’s a SEM?
(Scanning Electron Microscope)
Scans beams of electrons across specimen
2.1.0 Foundations in Biology: SEM
What are the Advantages of using a SEM?
- 1nm max resolution
- x500,000 max mag
- Not alive
↳ surface of specimen - 3D
2.1.0 Foundations in Biology: SEM
What are the Disadvantages of using a SEM?
- Expensive
- Black & White
2.1.0 Foundations in Biology: Pre-prepared slides
What occurs in the Fixation stage?
Chemicals preserve material in life like condition
2.1.0 Foundations in Biology: Pre-prepapred slides
Why does the Fixation stage occur?
So specimen isn’t distorted
2.1.0 Foundations in Biology: Pre-prepared slides
What occurs in the Dehydration stage?
Water is removed from specimen using ethanol
2.1.0 Foundations in Biology: Pre-prepared slides
Why does the Dehydration stage occur??
Important for electron microscope
↳ water molecules deflect electron beam → blurs image
2.1.0 Foundations in Biology: Pre-prepared slides
What occurs in the Embedding stage?
Supports the tissue in wax/resin
↳ so it can be cut into sections
2.1.0 Foundations in Biology: Pre-prepared slides
Why does the Embedding stage occur?
- Sectioning produces very thin slices of mounting
- Sections are cut to make them a few um (light microscope) or nm(electron microscope)
2.1.0 Foundations in Biology: Pre-prepared slides
Why is Staining used?
Cell material = transparent
* Staining used → increase contrast between different structures
2.1.0 Foundations in Biology: Pre-prepared slides
Why is Mounting used?
Protects material so its suitable for viewing over a long period
2.1.0 Foundations in Biology: Setting up a slide
How would you set up a Dry Mount?
- Thin slice (sectioning) using a sharp knife
↳ increases resolution → light can pass through it - Place coverslip on top
2.1.0 Foundations in Biology: Setting up a slide
How would you set up a Wet Mount?
- Pipette small amounts of water onto the slide
- Use tweezers to place specimen
- Use a coverslip at an angle
↳ avoid trapping air bubbles - Add stain to one side of the coverslip
