A2.2.3 - Advanced Microscopy

Question 1

Advantages of EMs

Answer 1

• Utilizes a beam of electrons (≠ light)
• Electrons have shorter wavelengths → resolutions greater by x1,000 & objects can magnify over x500,000

Question 2

What are the 2 general types of EMs

Answer 2

• Scanning Electron Microscope (SEM)
  → Scans surface of specimen
• Transmission Electron Microscope (TEM)
  → Beam concentrated to a very thin section of specimen

Question 3

What are the 2 techniques of EMs

Answer 3

• Freeze Fracture (FF-em)
  → Preparation of sample; rapid freezing
  → Sample broken into smaller pieces (fracturing)
  → Allows the viewing of the internal structure
• Cryogenic Electron Microscopy (Cryo-em)
  → Freezing sample to cryogenic temp. (-180°C)

Question 4

What are the 2 techniques of LMs

Answer 4

• Immunofluorescence
  → Fluorophore is attached to antibodies targeted for specific antigens
  → Brightly coloured spots when shone with a certain wavelength of light
  → Dyes that combine with certain cellular components
  → Brightly coloured spots when shone with UV or violet-blue lights

Question 4

Define ‘resolution’

Answer 4

The shortest distance between 2 separate points in a microscope’s FOV that can still be distinguished as separate objects

Question 5

Can LMs view viruses?

Answer 5

No. LMs have low resolutions which makes it impossible to distinguish viruses as separate objects from its surroundings since viruses are incredibly small (20~200nm in diameter)