week 1 - intro

Question 1

microbiology

Answer 1

• Study of organisms which cant be seen with the naked eye
• Study of microorganisms
  o Viruses, bacteria, fungi, algae, protozoa

Question 2

importance of microbiology

Answer 2

• Biotechnology
• Health and disease
• Ecology

Question 3

methods of study

Answer 3

• Microscopy
• Culture on plates or in broth

Question 4

microscopy

Answer 4

• Magnification
  o Objective X ocular
  o Maximun ~x1500
• Resolution
  o Limit of resolution for light microscope is about 0.2 um

Question 5

light microscopy

Answer 5

• Bright field
  o Often stained specimens
• Phase contrast
  o Unstained

Question 6

electron microscopry
scanning

Answer 6

• Scanning electron microscopy (SEM)
  o External features
  o Intact cells and appendages
  o Specimen coated in heavy metal (gold)
  o 3D images
  o Magnification 15x to 100,000x

Question 7

electron microsocpy
transmission

Answer 7

• Transmission electron microscope (TEM)
  o Study internal structures
  o Thin section of whole cells
  o Negative staining with heavy metals (osmium, lead, uranium)
   This damages cells)
  o Much higher resolving power
  o Can see molecules

Question 8

fluorescent microscopy

Answer 8

• Detects florescence
  o Shine light at one wavelength
   Specimen emits light at another wavelength
  o Some materials fluoresce naturally
   E.g. chlorophyll
  o Biomolecules labelled with florescent dyes
  o Real time and in living cells

Question 9

Cryo-EM

Answer 9

• Sample cooled to cryogenic temps. And embedded in an environment of vitreous water
• Sample preparation
  o Samples are frozen very rapidly in ethane cooled by liquid nitrogen
  o The water becomes vitreous
• Image analysis
  o Thousands of 2D images are aligned and “averaged”
  o 2D sliced are reconstructed to give the 3D image.