CH 2 Lecture Flashcards
What book?
Micrographia
Who made first book about microscopic observations?
Robert Hooke
First person to observe bacteria?
Anton van Leeuwenhoek
First man to make a light microscope to view MICROBES?
Anton van Leeuwenhoek
What did Anton van Leeuwenhoek used to call microorganisms?
Animalcules
Who created the compound microscope?
Galileo Galilei
Who perfected the optical objective lens?
Joseph Jackson Lister
What year was electron microscope discovered?
1940
2 MAIN TYPES of LIGHT MICROSCOPE?
- Simple (1 lens, short focal length, ~300x)
- Compound or Complex (2 set of lenses, ~1000x)
2 MAIN TYPES of ELECTRON MICROSCOPES
- Scanning (electron beam moves back and forth)
- Transmission (electron beam penetrates the cell)
4 CHARACTERISTICS OF A GOOD MICROSCOPE
- Adequate m___ p___
- High r____ p____
- Provide good c___
- Serves your p___
- magnifying power
- resolving power
- contrast
- purpose
OTHER types of LIGHT microscope
- Used for thick biofilms
- Use fluorochromes, chemical
- Used for specimens that cannot be stained
4 Used for detailed examination of INTERNAL STRUCTURE
5 visualizes specimens that fluoresce
6 Detection of immunological reactions
7 Used to examine living cells
8 Based on variations of REFRACTIVE INDICES but with diffraction halo
9 Based on variations of REFRACTIVE INDICES but with NO diffraction halo
10 Object is dark, bg is light
11 Bg is dark, object is light
12 Used for specimens invisible in ordinary light
- Confocal
- Fluorescence
- Dark Field
- Phase contrast
- Fluorescence
- Fluorescence
- Two-photon
- Phase contrast
- DIFFERENTIAL
INTERFERENCE CONTRAST
10 Bright Field
11 Dark Field - Dark Field
Can the electron microscope be used to observe living organisms?
no
TRANSMISSION VS SCANNING ELECTRON MICRSCOPE
transmission
- observer ultrastructure
- viruses
scanning
- only surface features
- 3d
ADVANTAGES and DISADVANTAGES of examining living microogranisms
Ad:
- undistorted characteristics
- celullar processes
- motility
simple to prepare
Disad: refractive index similar to water (difficult to observe)
2 Techniques to observe LIVING ORGANISMS
- Wet mount
- Hanging Drop
ADVANTAGES and DISADVANTAGES of stained preparations
Ad:
- provide contrast
- preserved
- killed
Disad
- more complicated to prepare
- more expensive
1st step of staining microorganisms (DEFINITION of smear)
SMEAR PREPARATION
- THIN and DRY film of microorganisms left to DRY
2nd step of staining microorganisms ( 2 types )
FIXATION - kills cells and makes them sticky to increase apparent diameters
- Heat (direct flame)
- Chemical (alcohol) to preserve properties as much as possible
3rd step of staining microorganisms
STAINING
-application of biological dyes
DYE - chromophric ions
3 TYPES OF STAINS
- BASIC (positively charged dye) - mostly used
- ACIDIC (negative)
- Neutral
What staining procedure uses only ONE DYE
SIMPLE STAINING
What SIMPLE staining procedure use a dye with the same colour of the cells?
POSITIVE/direct
Why is ^^ called positive?
- cells are usually negatively charged kaya didikit sya to enhance the appearance of cells for observation
